Quartz is found in almost every geological environment. It is a common constituent in most of the rock types and soil groups. Granite, sandstone, limestone, and most of the igneous, sedimentary, and metamorphic rocks contain quartz. Quartz contains mainly oxygen and silicon. These two constituents make upto 75 % of the earth’s crust. An alternate name for the Quartz Group is the Silica Group.
This document provides a summary of alkali feldspar and plagioclase feldspar. It discusses their crystal structure, composition, physical and optical properties, paragenesis, and applications. Alkali feldspar includes orthoclase, sanidine, and microcline. Plagioclase feldspar is a solid solution between albite and anorthite. Both have important industrial uses such as in ceramics, glass, paints, plastics, and as gemstones. The document is presented by Atish Kumar Sahoo for his MTech course at the Department of Applied Geology.
Garnet is a group of six silicate minerals that are isomorphous and never occur in pure form. They vary slightly in properties but can be indistinguishable without analysis. Garnets have the general formula X3Y2(SiO4)3 and consist of silicon tetrahedrons linked to distorted metal octahedrons, forming a cubic crystal structure. They commonly occur as dodecahedrons or trapezohedrons and vary in color from red to green to black. Garnets are used as abrasives, for water jet cutting, filtration, and as gemstones due to their variety of colors and hardness.
The pyroxene group of minerals is a type of inosilicate that contains chains of silica tetrahedrons. There are two main types: single chain and double chain structures. This determines the cleavage angles and forms of the minerals. Common pyroxene minerals include augite, diopside, enstatite, and jadeite. They are found in mafic and ultramafic igneous rocks as well as various metamorphic rock types.
Introduction; Chemical composition of garnet; Structure; Classification; Physical properties; Optical properties; Occurrences; Gem variety; and Uses
Garnet group of minerals is one of the important group of minerals.
Since they are found in wide variety of colours, they are also used as gemstones.
Garnet group of minerals are also abrasives and thus have various industrial applications.
1. Wall rock alteration occurs when hot hydrothermal fluids interact with surrounding country rocks, changing their mineralogy. There are two main types: hypogene alteration from ascending fluids and supergene alteration from descending waters.
2. Alteration products depend on the rock character, fluid properties like pH and temperature/pressure conditions. Important reactions include hydrolysis, hydration, dechlorination, silication, and decarbonation.
3. Different alteration types are associated with certain deposit types, like potassic alteration with porphyry copper deposits and greisenization indicating tin or tungsten. Original rock type influences prevalent alteration, such as sericitization and silicification in acidic rocks.
This document provides information about the mineral olivine. It begins with an introduction to olivine, noting its color and importance as a rock-forming mineral. It then discusses the members of the olivine family, their weathering, solid solution behavior, and position in Bowen's reaction series. The remainder of the document covers olivine's structure, alteration, high-pressure polymorphs, physical and optical properties, paragenesis, significance, and examples of occurrences. Diagrams and images supplement the detailed information presented.
This document provides an overview of sedimentary rocks and the process of diagenesis. It discusses how sediments are deposited and buried over time, undergoing physical and chemical changes through compaction, cementation, and other diagenetic processes. These changes occur due to increasing pressure and temperature with depth and alter the sediments' properties, converting them into consolidated sedimentary rocks. The document also examines factors that control diagenesis like composition, porosity, and permeability, and it outlines the major diagenetic processes and their effects on the physical, mineralogical, and chemical characteristics of sediments.
The document discusses the olivine group of minerals. It describes the history of the term "olivine" and defines key members of the olivine group. Olivine is a common mineral found in mafic and ultramafic igneous rocks. It is the first mineral to crystallize from cooling magma due to its high melting temperature. Olivine weathers quickly on Earth's surface, breaking down to form fertile volcanic soils. It has various industrial and gemstone uses.
This document provides a summary of alkali feldspar and plagioclase feldspar. It discusses their crystal structure, composition, physical and optical properties, paragenesis, and applications. Alkali feldspar includes orthoclase, sanidine, and microcline. Plagioclase feldspar is a solid solution between albite and anorthite. Both have important industrial uses such as in ceramics, glass, paints, plastics, and as gemstones. The document is presented by Atish Kumar Sahoo for his MTech course at the Department of Applied Geology.
Garnet is a group of six silicate minerals that are isomorphous and never occur in pure form. They vary slightly in properties but can be indistinguishable without analysis. Garnets have the general formula X3Y2(SiO4)3 and consist of silicon tetrahedrons linked to distorted metal octahedrons, forming a cubic crystal structure. They commonly occur as dodecahedrons or trapezohedrons and vary in color from red to green to black. Garnets are used as abrasives, for water jet cutting, filtration, and as gemstones due to their variety of colors and hardness.
The pyroxene group of minerals is a type of inosilicate that contains chains of silica tetrahedrons. There are two main types: single chain and double chain structures. This determines the cleavage angles and forms of the minerals. Common pyroxene minerals include augite, diopside, enstatite, and jadeite. They are found in mafic and ultramafic igneous rocks as well as various metamorphic rock types.
Introduction; Chemical composition of garnet; Structure; Classification; Physical properties; Optical properties; Occurrences; Gem variety; and Uses
Garnet group of minerals is one of the important group of minerals.
Since they are found in wide variety of colours, they are also used as gemstones.
Garnet group of minerals are also abrasives and thus have various industrial applications.
1. Wall rock alteration occurs when hot hydrothermal fluids interact with surrounding country rocks, changing their mineralogy. There are two main types: hypogene alteration from ascending fluids and supergene alteration from descending waters.
2. Alteration products depend on the rock character, fluid properties like pH and temperature/pressure conditions. Important reactions include hydrolysis, hydration, dechlorination, silication, and decarbonation.
3. Different alteration types are associated with certain deposit types, like potassic alteration with porphyry copper deposits and greisenization indicating tin or tungsten. Original rock type influences prevalent alteration, such as sericitization and silicification in acidic rocks.
This document provides information about the mineral olivine. It begins with an introduction to olivine, noting its color and importance as a rock-forming mineral. It then discusses the members of the olivine family, their weathering, solid solution behavior, and position in Bowen's reaction series. The remainder of the document covers olivine's structure, alteration, high-pressure polymorphs, physical and optical properties, paragenesis, significance, and examples of occurrences. Diagrams and images supplement the detailed information presented.
This document provides an overview of sedimentary rocks and the process of diagenesis. It discusses how sediments are deposited and buried over time, undergoing physical and chemical changes through compaction, cementation, and other diagenetic processes. These changes occur due to increasing pressure and temperature with depth and alter the sediments' properties, converting them into consolidated sedimentary rocks. The document also examines factors that control diagenesis like composition, porosity, and permeability, and it outlines the major diagenetic processes and their effects on the physical, mineralogical, and chemical characteristics of sediments.
The document discusses the olivine group of minerals. It describes the history of the term "olivine" and defines key members of the olivine group. Olivine is a common mineral found in mafic and ultramafic igneous rocks. It is the first mineral to crystallize from cooling magma due to its high melting temperature. Olivine weathers quickly on Earth's surface, breaking down to form fertile volcanic soils. It has various industrial and gemstone uses.
Igneous rock textures are controlled by cooling rate, with rapid cooling resulting in smaller crystals and slower cooling allowing larger crystals to form. Textures provide information about cooling/crystallization rates and phase relations during crystallization. Textures describe grain features like size, shape, orientation, and boundaries, seen in hand samples or microscopically. Common textures include phaneritic (with evident crystals), porphyritic (with larger phenocrysts in fine-grained groundmass), and graphic (with exsolved minerals forming angular shapes). Compositionally zoned crystals also occur.
Mantle melting occurs when heat and pressure cause partial melting of the mantle, producing basaltic magma. Basalt is the most common volcanic rock on Earth and can be further differentiated to form other igneous rock types. Evidence for the composition and processes of the mantle comes from ophiolites, dredged samples from ocean floors, nodules contained in basalts, and xenoliths brought up from deep in the mantle via kimberlite eruptions. Together this evidence indicates that the upper mantle is composed predominantly of the minerals olivine, orthopyroxene, and clinopyroxene which make up the rocks dunite, harzburgite, and lherzol
This document provides information about amphibole group minerals. It discusses that amphiboles are double chain silicates that share properties with pyroxenes. Amphiboles have a Si:O ratio of 4:11, contain essential hydroxyl groups, and form prismatic or needle-like crystals. Several monoclinic and orthorhombic amphibole group minerals are described in detail, including their chemical formulas, crystal structures, typical occurrences, and physical properties. Prominent amphibole deposits in India are also listed.
This document provides an overview of the mineral olivine, beginning with its classification as a nesosilicate. It describes olivine's isolated tetrahedral structure and solid solution with forsterite and fayalite. Physical and optical properties of both minerals are outlined. The document discusses olivine's significance in petrology as a mantle constituent and provenance indicator. High-pressure polymorphs and economic uses of olivine are also mentioned.
The document discusses the geology of the Singhbhum Craton located in northern Odisha and Jharkhand, India. It is known for its rich iron and copper deposits. The craton contains several rock groups from the Archean to Paleoproterozoic periods that record its tectonic evolution. The oldest rocks are the Older Metamorphic Group composed of schists and gneisses. Overlying are the iron-rich rocks of the Iron Ore Group. Later intrusions included the Singhbhum Granite batholith and sediments make up the Singhbhum, Dhanjori, and Gangpur Groups. The stratigraphy and structure of the craton provide evidence of its early
The document describes a petrographic study of rocks in the Vallanadu area of Tamil Nadu, India. It finds that the main rock types in the area are charnockites, khondalites, cordierite gneisses, calc-silicate rocks, and grey and pink granites. Two sets of conjugate shear systems are observed, including a NW-SE dextral shear zone conjugating with a NE-SW sinistral zone. Granites in the area formed syntectonically. The Vallanadu area experienced initial ductile deformation followed by brittle-ductile deformation during the Neoproterozoic to Cambrian period.
This document discusses the pyroxene group of minerals. Pyroxenes are an important group of rock-forming silicate minerals found in igneous and metamorphic rocks. They are classified as orthorhombic or monoclinic pyroxenes based on their crystal structure. Common orthorhombic pyroxenes include enstatite, ferrosilite, and pigeonite. Important monoclinic pyroxenes include diopside, hedenbergite, augite, aegirine, jadeite, and spodumene. Pyroxenoids like wollastonite are also discussed. The document details the composition, properties and occurrence of these different pyroxene group
The document discusses anorthosite, an intrusive igneous rock composed of 90-100% plagioclase feldspar. It describes the mineralogy, texture, and classification of anorthosite. Proteroic anorthosite formed during the Proterozoic era while Archean anorthosite formed during the Archean and are characterized by calcic plagioclase. Anorthosite is also found on the moon and classified as lunar anorthosite. Some anorthosite deposits are mined for titanium, iron, gemstones, and aluminum.
This document discusses metamorphic facies and key concepts in metamorphic petrology. It defines metamorphic facies as ranges of mineral assemblages that form under similar pressure-temperature conditions, regardless of the original rock type. Several classic metamorphic zones defined by index minerals are described, as well as variations that depend on bulk rock composition. The document also outlines the major metamorphic facies series and explains how they relate to tectonic settings like subduction zones and orogenic belts.
Extinction angle and Types of Extinction in Minerals.pdfAasishGiri
Extinction refers to the dimming of light when viewed through a mineral under cross-polarized light in a petrographic microscope. There are four main types of extinction: parallel extinction occurs when the mineral's long axis or cleavage plane is parallel to the vibration direction of light; inclined extinction occurs when these are not parallel in monoclinic and triclinic minerals; symmetrical extinction occurs when the vibration direction bisects two cleavage planes; and some minerals lack distinct cleavage planes and therefore have no measurable extinction angle. The extinction angle is the amount of rotation required for a mineral to become extinct and is a diagnostic characteristic.
The document discusses different types of intrusive igneous rock bodies, known as plutons. It describes concordant plutons, which include sills, laccoliths, lopoliths, phacoliths, and bysmaliths. Sills are thin, tabular bodies that spread parallel to bedding planes. Laccoliths have a flat floor and domed roof, causing folding of overlying rock layers. Lopoliths are large, basin-shaped bodies with nearly flat tops and convex bottoms. Phacoliths and bysmaliths are also concordant bodies that form along folded strata. The document provides diagrams and examples of each type of concordant
Isomorphism refers to substances with analogous formulas that have closely related crystal structures. Mitscherlich first introduced the term in 1819 when he found that crystals of KH2PO4, KH2AsO4, (NH4)H2PO4 and (NH4)H2AsO4 showed the same forms and interfacial angles between corresponding faces were very similar, despite their different chemical compositions. Isomorphism is common among minerals and is the basis for how some minerals are classified into groups based on their crystal structure. Substances can be isomorphous even if their formulas do not appear analogous, as long as the ions are similar in size and coordination.
This document provides an overview of gemstones, including their physical and optical properties, shapes and cuts, and synthetics and simulants. It discusses the key properties used to identify gemstones such as crystal habit, specific gravity, hardness, refractive index, and luminescence. Different cutting styles including cabochon and faceted cuts are described. The document also covers synthetic gemstones which mimic natural stones, and simulants which have similar appearances but different properties. It aims to equip gemologists with the knowledge to distinguish natural gems from synthetics or enhanced stones.
Minerals used in Refractories and ceramicPramoda Raj
The document discusses various mineral raw materials used in the ceramic industry in India. The principal materials are silica in the form of quartz and other minerals, and alumino-silicates like feldspars and clays. Major sources of silica are quartzite, sandstone and high silica sands. Important feldspar sources are pegmatites in Rajasthan, Bihar and Andhra Pradesh. Ball clays are found in Rajasthan and Gujarat while china clay deposits exist across India. Refractory materials include fireclay, quartz, dolomite, magnesite, serpentine, olivine and chromite. The document also provides details on the
This document discusses the mineralogy, textures, types, and occurrences of granite. Granite is a common felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica. It forms large batholiths within the cores of mountain ranges. Granite varies in composition but contains at least 20% quartz and can be classified based on percentages of quartz, alkali feldspar, and plagioclase feldspar. Common types include mica granite, biotite-hornblende granite, and pyroxene granite.
This document provides an overview of kimberlites, including their mineralogy, morphology, petrology, classification, origin, and economic importance. Kimberlites occur as vertical carrot-shaped intrusions called pipes and have an inequigranular texture consisting of large crystals in a fine-grained matrix. They are classified into Group I and Group II based on isotopic affinities. Kimberlites originate at depths of 100-200 km in the mantle and are emplaced explosively due to their high volatile content, forming diatremes with features like angular fragments. Kimberlites are economically important as the primary source of diamonds, though only 1 in 200 pipes contain gem-quality diamonds.
There are two main forms of igneous rocks:
1) Extrusive rocks form from lava erupted at the Earth's surface and cool rapidly. They include lava flows, pyroclastic deposits like volcanic ash and tuff.
2) Intrusive rocks form from magma that cools below the surface. They can be concordant, forming sheets and domes parallel to layers, like sills and laccoliths, or discordant and cutting across layers, like dikes, batholiths, and volcanic necks.
Name: Probably used in the mineralogical sense by 1706 and originally "smicka" and from the Latin micare - to flash or glisten in allusion to the material's appearance. Isinglass predates the use of mica as a mineral term and known from at least 1535, but isinglass also referred to the matter from the sturgeon fish that also had pearly flakes from the scales.
Mica is widely distributed and occurs in igneous, metamorphic and sedimentary regimes. Mica group represents 34 phyllosilicate minerals that exhibits a layered or platy structure. Commercially important mica minerals are muscovite (potash or white mica) and phlogopite (magnesium or amber mica). Granitic pegmatites are the source of muscovite sheet, while phlogopite is found in areas of metamorphosed sedimentary rocks into which pegmatite rich granite rocks have been intruded. It possesses highly perfect basal cleavage due to which it can easily and accurately split into very thin sheets or films of any specified thickness. It has a unique combination of elasticity, toughness, flexibility and transparency. It possesses resistance to heat and sudden change in temperature and high dielectric strength. It is chemically inert, stable and does not absorb water.
Quartz is a mineral composed of silicon and oxygen atoms arranged in a continuous framework of silicon-oxygen tetrahedra. It exists in two forms, alpha-quartz and high-temperature beta-quartz. Quartz undergoes an abrupt transformation between these two forms at 573 degrees Celsius. It is the second most abundant mineral in Earth's continental crust after feldspar. There are several colored varieties of quartz described, including rose quartz, amethyst, citrine, and smoky quartz.
Quartz is one of the most abundant minerals and is composed of silicon dioxide (SiO2). It has a complex crystal structure and exists in several polymorphs including alpha-quartz, beta-quartz, tridymite, cristobalite, coesite, and stishovite. The stability of these polymorphs depends on temperature and pressure conditions. Cryptocrystalline varieties of quartz include chalcedony, agate, jasper, chert, and flint. Macrocrystalline varieties include rock crystal, milky quartz, amethyst, rose quartz, citrine, and smoky quartz.
Igneous rock textures are controlled by cooling rate, with rapid cooling resulting in smaller crystals and slower cooling allowing larger crystals to form. Textures provide information about cooling/crystallization rates and phase relations during crystallization. Textures describe grain features like size, shape, orientation, and boundaries, seen in hand samples or microscopically. Common textures include phaneritic (with evident crystals), porphyritic (with larger phenocrysts in fine-grained groundmass), and graphic (with exsolved minerals forming angular shapes). Compositionally zoned crystals also occur.
Mantle melting occurs when heat and pressure cause partial melting of the mantle, producing basaltic magma. Basalt is the most common volcanic rock on Earth and can be further differentiated to form other igneous rock types. Evidence for the composition and processes of the mantle comes from ophiolites, dredged samples from ocean floors, nodules contained in basalts, and xenoliths brought up from deep in the mantle via kimberlite eruptions. Together this evidence indicates that the upper mantle is composed predominantly of the minerals olivine, orthopyroxene, and clinopyroxene which make up the rocks dunite, harzburgite, and lherzol
This document provides information about amphibole group minerals. It discusses that amphiboles are double chain silicates that share properties with pyroxenes. Amphiboles have a Si:O ratio of 4:11, contain essential hydroxyl groups, and form prismatic or needle-like crystals. Several monoclinic and orthorhombic amphibole group minerals are described in detail, including their chemical formulas, crystal structures, typical occurrences, and physical properties. Prominent amphibole deposits in India are also listed.
This document provides an overview of the mineral olivine, beginning with its classification as a nesosilicate. It describes olivine's isolated tetrahedral structure and solid solution with forsterite and fayalite. Physical and optical properties of both minerals are outlined. The document discusses olivine's significance in petrology as a mantle constituent and provenance indicator. High-pressure polymorphs and economic uses of olivine are also mentioned.
The document discusses the geology of the Singhbhum Craton located in northern Odisha and Jharkhand, India. It is known for its rich iron and copper deposits. The craton contains several rock groups from the Archean to Paleoproterozoic periods that record its tectonic evolution. The oldest rocks are the Older Metamorphic Group composed of schists and gneisses. Overlying are the iron-rich rocks of the Iron Ore Group. Later intrusions included the Singhbhum Granite batholith and sediments make up the Singhbhum, Dhanjori, and Gangpur Groups. The stratigraphy and structure of the craton provide evidence of its early
The document describes a petrographic study of rocks in the Vallanadu area of Tamil Nadu, India. It finds that the main rock types in the area are charnockites, khondalites, cordierite gneisses, calc-silicate rocks, and grey and pink granites. Two sets of conjugate shear systems are observed, including a NW-SE dextral shear zone conjugating with a NE-SW sinistral zone. Granites in the area formed syntectonically. The Vallanadu area experienced initial ductile deformation followed by brittle-ductile deformation during the Neoproterozoic to Cambrian period.
This document discusses the pyroxene group of minerals. Pyroxenes are an important group of rock-forming silicate minerals found in igneous and metamorphic rocks. They are classified as orthorhombic or monoclinic pyroxenes based on their crystal structure. Common orthorhombic pyroxenes include enstatite, ferrosilite, and pigeonite. Important monoclinic pyroxenes include diopside, hedenbergite, augite, aegirine, jadeite, and spodumene. Pyroxenoids like wollastonite are also discussed. The document details the composition, properties and occurrence of these different pyroxene group
The document discusses anorthosite, an intrusive igneous rock composed of 90-100% plagioclase feldspar. It describes the mineralogy, texture, and classification of anorthosite. Proteroic anorthosite formed during the Proterozoic era while Archean anorthosite formed during the Archean and are characterized by calcic plagioclase. Anorthosite is also found on the moon and classified as lunar anorthosite. Some anorthosite deposits are mined for titanium, iron, gemstones, and aluminum.
This document discusses metamorphic facies and key concepts in metamorphic petrology. It defines metamorphic facies as ranges of mineral assemblages that form under similar pressure-temperature conditions, regardless of the original rock type. Several classic metamorphic zones defined by index minerals are described, as well as variations that depend on bulk rock composition. The document also outlines the major metamorphic facies series and explains how they relate to tectonic settings like subduction zones and orogenic belts.
Extinction angle and Types of Extinction in Minerals.pdfAasishGiri
Extinction refers to the dimming of light when viewed through a mineral under cross-polarized light in a petrographic microscope. There are four main types of extinction: parallel extinction occurs when the mineral's long axis or cleavage plane is parallel to the vibration direction of light; inclined extinction occurs when these are not parallel in monoclinic and triclinic minerals; symmetrical extinction occurs when the vibration direction bisects two cleavage planes; and some minerals lack distinct cleavage planes and therefore have no measurable extinction angle. The extinction angle is the amount of rotation required for a mineral to become extinct and is a diagnostic characteristic.
The document discusses different types of intrusive igneous rock bodies, known as plutons. It describes concordant plutons, which include sills, laccoliths, lopoliths, phacoliths, and bysmaliths. Sills are thin, tabular bodies that spread parallel to bedding planes. Laccoliths have a flat floor and domed roof, causing folding of overlying rock layers. Lopoliths are large, basin-shaped bodies with nearly flat tops and convex bottoms. Phacoliths and bysmaliths are also concordant bodies that form along folded strata. The document provides diagrams and examples of each type of concordant
Isomorphism refers to substances with analogous formulas that have closely related crystal structures. Mitscherlich first introduced the term in 1819 when he found that crystals of KH2PO4, KH2AsO4, (NH4)H2PO4 and (NH4)H2AsO4 showed the same forms and interfacial angles between corresponding faces were very similar, despite their different chemical compositions. Isomorphism is common among minerals and is the basis for how some minerals are classified into groups based on their crystal structure. Substances can be isomorphous even if their formulas do not appear analogous, as long as the ions are similar in size and coordination.
This document provides an overview of gemstones, including their physical and optical properties, shapes and cuts, and synthetics and simulants. It discusses the key properties used to identify gemstones such as crystal habit, specific gravity, hardness, refractive index, and luminescence. Different cutting styles including cabochon and faceted cuts are described. The document also covers synthetic gemstones which mimic natural stones, and simulants which have similar appearances but different properties. It aims to equip gemologists with the knowledge to distinguish natural gems from synthetics or enhanced stones.
Minerals used in Refractories and ceramicPramoda Raj
The document discusses various mineral raw materials used in the ceramic industry in India. The principal materials are silica in the form of quartz and other minerals, and alumino-silicates like feldspars and clays. Major sources of silica are quartzite, sandstone and high silica sands. Important feldspar sources are pegmatites in Rajasthan, Bihar and Andhra Pradesh. Ball clays are found in Rajasthan and Gujarat while china clay deposits exist across India. Refractory materials include fireclay, quartz, dolomite, magnesite, serpentine, olivine and chromite. The document also provides details on the
This document discusses the mineralogy, textures, types, and occurrences of granite. Granite is a common felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica. It forms large batholiths within the cores of mountain ranges. Granite varies in composition but contains at least 20% quartz and can be classified based on percentages of quartz, alkali feldspar, and plagioclase feldspar. Common types include mica granite, biotite-hornblende granite, and pyroxene granite.
This document provides an overview of kimberlites, including their mineralogy, morphology, petrology, classification, origin, and economic importance. Kimberlites occur as vertical carrot-shaped intrusions called pipes and have an inequigranular texture consisting of large crystals in a fine-grained matrix. They are classified into Group I and Group II based on isotopic affinities. Kimberlites originate at depths of 100-200 km in the mantle and are emplaced explosively due to their high volatile content, forming diatremes with features like angular fragments. Kimberlites are economically important as the primary source of diamonds, though only 1 in 200 pipes contain gem-quality diamonds.
There are two main forms of igneous rocks:
1) Extrusive rocks form from lava erupted at the Earth's surface and cool rapidly. They include lava flows, pyroclastic deposits like volcanic ash and tuff.
2) Intrusive rocks form from magma that cools below the surface. They can be concordant, forming sheets and domes parallel to layers, like sills and laccoliths, or discordant and cutting across layers, like dikes, batholiths, and volcanic necks.
Name: Probably used in the mineralogical sense by 1706 and originally "smicka" and from the Latin micare - to flash or glisten in allusion to the material's appearance. Isinglass predates the use of mica as a mineral term and known from at least 1535, but isinglass also referred to the matter from the sturgeon fish that also had pearly flakes from the scales.
Mica is widely distributed and occurs in igneous, metamorphic and sedimentary regimes. Mica group represents 34 phyllosilicate minerals that exhibits a layered or platy structure. Commercially important mica minerals are muscovite (potash or white mica) and phlogopite (magnesium or amber mica). Granitic pegmatites are the source of muscovite sheet, while phlogopite is found in areas of metamorphosed sedimentary rocks into which pegmatite rich granite rocks have been intruded. It possesses highly perfect basal cleavage due to which it can easily and accurately split into very thin sheets or films of any specified thickness. It has a unique combination of elasticity, toughness, flexibility and transparency. It possesses resistance to heat and sudden change in temperature and high dielectric strength. It is chemically inert, stable and does not absorb water.
Quartz is a mineral composed of silicon and oxygen atoms arranged in a continuous framework of silicon-oxygen tetrahedra. It exists in two forms, alpha-quartz and high-temperature beta-quartz. Quartz undergoes an abrupt transformation between these two forms at 573 degrees Celsius. It is the second most abundant mineral in Earth's continental crust after feldspar. There are several colored varieties of quartz described, including rose quartz, amethyst, citrine, and smoky quartz.
Quartz is one of the most abundant minerals and is composed of silicon dioxide (SiO2). It has a complex crystal structure and exists in several polymorphs including alpha-quartz, beta-quartz, tridymite, cristobalite, coesite, and stishovite. The stability of these polymorphs depends on temperature and pressure conditions. Cryptocrystalline varieties of quartz include chalcedony, agate, jasper, chert, and flint. Macrocrystalline varieties include rock crystal, milky quartz, amethyst, rose quartz, citrine, and smoky quartz.
This document provides information about mineralogy, including the definition of a mineral, modes of mineral formation, crystallography, physical properties of minerals, and important rock-forming mineral groups. It discusses how minerals form from magma, secondary processes, and metamorphism. It also summarizes symmetry in crystals, Mohs hardness scale, cleavage, fracture, isomorphism, and silicate mineral structures. Major rock-forming silicates like feldspars, pyroxenes, and amphiboles are described in terms of their crystal systems, chemical compositions, and physical characteristics.
The document provides an overview of minerals and their properties. It discusses that minerals are naturally occurring inorganic solids with definite chemical compositions and crystal structures. It then covers various mineral groups including silicates, which are the most abundant mineral group composed of silica tetrahedra bonded together. Physical properties of minerals like crystal form, cleavage, luster, and hardness are also summarized as they are used to identify different minerals.
INTRODUCCIÓN A LOS ESTUDIOS DE MINERALES.pdfHenryBrown72
Introducción a los Minerales.
Manual para determinar los tipos de minerales, durante una exploración geológica.
Con este manual Usted determinara que tipo de mineral puede encontrar, de acuerdo a los indicios de tipo de roca y el análisis de mineralogía.
Es el mejor manual de cabecera para un geologo de exploraciones.
The document provides an overview of minerals, including their definition, classification, properties, and importance. It discusses that minerals are the building blocks of rocks and there are over 4,000 known types. Minerals have specific physical properties like crystal structure, hardness, and cleavage that allow them to be identified. The most abundant minerals in the Earth's crust are silicates, which make up the majority of rocks.
This document defines what a mineral is and describes its key properties. A mineral must be 1) naturally occurring 2) solid 3) have an orderly crystalline structure and well-defined chemical composition. Important identifying characteristics of minerals include crystal structure, hardness, color, streak, luster, fluorescence, and reaction to acid. Minerals are classified based on their main chemical elements, with silicates and carbonates being particularly important. Commercially valuable minerals can be extracted for metals, industrial uses, or as gemstones.
Mineral - naturally occurring, inorganic solid with orderly crystalline structure and a definite chemical composition.
These are the basic building blocks of rocks.
The document discusses rocks and minerals. It defines what minerals are, how they are identified, and where they come from. It also defines different types of rocks including igneous, sedimentary, and metamorphic rocks. It describes how rocks are formed and the rock cycle. Finally, it discusses the economic importance of minerals and how much the average person requires each year.
This document provides information on identifying common rock-forming minerals using their physical and chemical properties. It begins with an introduction to the learning competency and objectives. It then discusses the key physical properties used to identify minerals, including luster, hardness, crystal form, color, streak, cleavage, specific gravity, and other properties. It also covers the main chemical properties and groups of minerals, such as silicates, oxides, sulfates, sulfides, carbonates, native elements, and halides. The document provides examples and diagrams to illustrate mineral properties and identification techniques.
Minerals are naturally occurring inorganic solids with definite chemical compositions and crystalline atomic structures. There are over 4,000 known mineral types on Earth. Minerals form through natural geological processes as magma cools underground or ions crystallize out of solution. A mineral's crystal structure and properties like hardness, luster, streak, and cleavage can help identify different mineral types. Common rock-forming silicate minerals include feldspar and quartz, while calcite is a major carbonate mineral.
Minerals are naturally occurring inorganic solids with definite chemical compositions and crystalline atomic structures. There are over 4,000 known mineral types on Earth. Minerals form through natural geological processes as magma cools underground or ions crystallize out of solution. A mineral's crystal structure and properties like hardness, luster, streak, and cleavage can help identify different mineral types. Common rock-forming silicate minerals include feldspar and quartz, while calcite is a major carbonate mineral.
Minerals are naturally occurring inorganic solids with definite chemical compositions and crystalline atomic structures. There are over 4,000 known mineral types on Earth. Minerals form through natural geological processes as magma cools underground or ions crystallize out of solution. A mineral's crystal structure and properties like hardness, luster, streak, and cleavage can help identify different mineral types. Common rock-forming silicate minerals include feldspar and quartz, while calcite is a major carbonate mineral.
Minerals are naturally occurring inorganic solids with definite chemical compositions and crystalline atomic structures. There are over 4,000 known mineral types on Earth. Minerals form through natural geological processes as magma cools underground or ions crystallize out of solution. A mineral's crystal structure and properties like hardness, luster, streak, and cleavage can help identify different mineral types. Common rock-forming silicate minerals include feldspar and quartz, while calcite is a major carbonate mineral.
Minerals are naturally occurring inorganic solids with definite chemical compositions and crystalline atomic structures. There are over 4,000 known mineral types on Earth. Minerals form through natural geological processes as magma cools underground or ions crystallize out of solution. A mineral's crystal structure and properties like hardness, luster, streak, and cleavage can help identify different mineral types. Common rock-forming silicate minerals include feldspar and quartz, while calcite is a major carbonate mineral.
Minerals are naturally occurring inorganic crystalline solids with a definite chemical composition and physical properties. The study of minerals is called mineralogy. Minerals can be identified by their crystal structure, hardness, luster, color, density and other physical properties. The most abundant elements in Earth's crust are oxygen, silicon, aluminum, iron, calcium, magnesium, sodium and potassium. Minerals form through processes such as cooling of magma, evaporation of briny liquids, and precipitation from fluids. Rocks are assemblages of minerals or mineraloids in a solid state and can be igneous, sedimentary or metamorphic.
The document provides information on rocks and minerals. It begins by defining a mineral as a naturally occurring, inorganic solid with a definite chemical composition and crystalline structure. Minerals can be identified based on their physical properties like color, streak, luster, hardness, cleavage, and crystal shape. Rocks are composed of two or more minerals and are classified based on their formation process as igneous, sedimentary, or metamorphic. Igneous rocks form from cooling magma, sedimentary rocks form through compaction and cementation of sediments, and metamorphic rocks form from changes to existing rocks through heat, pressure, and chemical activity.
Minerals are naturally occurring inorganic solids with definite chemical compositions and ordered atomic structures. They form through natural geological processes on or inside Earth. Key properties used to identify minerals include hardness, luster, specific gravity, streak, and cleavage/fracture. Minerals have many important uses beyond gems, including as sources of useful elements like iron, aluminum, and titanium that are integral to infrastructure, transportation, and technology.
Ring n chain compounds
Silicates
Types of silicates
Principle of Silicate minerals
Soluble silicates
Amphiboles, Zeolites, Ultramarines,
Feldspars
Silicates in technology
Glass, quartz, micas
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Quartz group of minerals
1. 1
QUARTZ GROUP OF MINERALS
By
Prof A. BALASUBRAMANIAN
CENTRE FOR ADVANCED STUDIES IN EARTH SCIENCE
UNIVERSITY OF MYSORE
MYSORE-6
2. 2
Introduction:
Minerals are valuable natural resources. Minerals are natural compounds formed through various
geological processes. More than 2000 minerals have been identified so far in different geological
environments. Minerals have unique physical properties, optical properties, crystal structure and
chemical composition. Because of their uniqueness, it is easy to identify any of them and use them
effectively. All the minerals are classified into different groups based on their chemical composition.
Among the major mineral groups, the most abundant ones are the quartz group of minerals.
Quartz is found in almost every geological environment. It is a common constituent in most of the rock
types and soil groups. Granite, sandstone, limestone, and most of the igneous, sedimentary, and
metamorphic rocks contain quartz. Quartz contains mainly oxygen and silicon. These two constituents
make upto 75 % of the earth’s crust. An alternate name for the Quartz Group is the Silica Group.
In this module, the following aspects of quartz are highlighted:
1. Importance and uniqueness of quartz
2. Physical, chemical and optical properties
3. Varieties of quartz
4. Occurrence and crystallization of quartz
5. Uses of quartz
Importance and uniqueness of quartz
Quartz is ubiquitous, plentiful and durable. It is chemically inert in contact with most substances. Quartz
occurs in hydrothermal veins and pegmatite. Well-formed crystals may reach several metres in length and
weigh hundreds of kilograms. It has electrical properties and heat resistance that make it valuable in
electronic products. Its luster, color and diaphaneity make it useful as a gemstone and also in the making
of glass. It has a hexagonal crystal structure and is made of trigonal crystallized silica.
Some quartz crystal structures are piezoelectric and are used as oscillators in electronic devices such as
quartz clocks and radios. An amorphous (glass) SiO2, called Lechatelierite, is caused by lightning strikes
in sand, distinct from typical window glass that is impure.
And it was Nicolas Steno's study of Quartz, that paved the way for modern crystallography. He
discovered that no matter how distorted a quartz crystal is, the long prism faces always made a perfect 60
degree angle, when it is broken.
Quartz is highly resistant to both mechanical and chemical weathering. At surface temperatures and
pressures, ordinary quartz is the most stable form of silicon dioxide. This durability makes it the
dominant mineral of mountaintops and the primary constituent of beach, river and desert sand.
It will remain stable up to 573 degrees Celsius at 1 kilobar of pressure. As the pressure increases, the
temperature at which quartz will lose its stability also increases. There are two types of quartz are
recognized as alpha and beta quartz. Above 1300 degrees and at a pressure of approximately 35 kilobars,
only beta quartz (also known as high quartz) is stable. Beta quartz is not the same as normal quartz
which is actually called as alpha quartz. Beta quartz has higher symmetry, it is less dense and has a
slightly lower specific gravity.
There are three polymorphs of SiO2 existing in nature, as quartz, tridymite and cristobalite.
3. 3
Their temperature ranges of stability are also varied.
Let us see some of them.
(i) The first one is - quartz . It is stable at atmospheric temperatures and upto 573°C.
(ii) The -quartz is stable from 573°C to 870°C can exist metastably above 870°C.
(iii) The - tridymite, which is also belonging to this group, can exist at atmospheric
temperatures and upto 117°C. It is not a stable form in this range.
(iv) The -tridymite can exist above 163°C and is the stable form from 870°C to 1470°C, above
1470°C it can exist but it is unstable; it melts at 1670°C.
(v) The -Cristobalite; it can exist at atmospheric temperatures and upto 200°C-275°C by is not
the stable form in this range.
(vi) -Cristobalite: it can exist above 200°C-275°C and is stable from 1470°C to its melting
point, 1713°C.
A few substances that contain SiO2 are classified as mineraloids. They are opal, SiO2 - n(H2O) and a
very rare pure silica glass called lechatelierite, SiO2. Both of these are amorphous and therefore lack a
true crystal structure.
The most important distinction between types of quartz is that of macrocrystalline and the
microcrystalline or cryptocrystalline varieties. These are aggregates of crystals visible only under high
magnification. Chalcedony is a generic term for cryptocrystalline quartz. The cryptocrystalline varieties
are either translucent or mostly opaque, while the transparent varieties tend to be macrocrystalline.
Not all varieties of quartz are naturally occurring. Prasiolite , an olive coloured material, is produced by
heat treatment. Although citrine occurs naturally, the majority is the result of heat-treated amethyst.
Carnelian is widely heat-treated to deepen its colour. Because natural quartz is so often twinned , much
quartz used in industry is synthesized. Large, flawless and untwinned crystals are produced in an
autoclave via the hydrothermal process: emeralds are also synthesized in this fashion.
Physical, chemical and optical properties
Color of quartz is as variable as the spectrum. We also get some crystal clear quartz followed by white or
cloudy / milky quartz. The Luster is glassy to vitreous as crystals, while cryptocrystalline forms are
usually waxy to dull but can be vitreous. Quartz crystals are mostly transparent to translucent. The
cryptocrystalline forms can be translucent or opaque. Quartz crystallizes in the trigonal Crystal System.
Crystal Habits are again widely variable but the most common habit is the occurrence of hexagonal
prisms of quartz, terminated with a six sided pyramid. These may actually look like two rhombohedrons.
The Cleavage of quartz is very weak in three directions (rhombohedral). The Fracture is conchoidal.
The Hardness is 7. But it is less in cryptocrystalline forms. The Specific Gravity is 2.65 or less if
cryptocrystalline. The Streak is white. Striations on prism faces run perpendicular to the C axis of the
crystals. Quartz is piezoelectric . The index of refraction of quartz is 1.55.
Twinning of quartz is based on Common Dauphine law, Brazil law and Japan law. Tenacity-wise it is
very Brittle. Quartz is Optically Uniaxial positive(+).
Many minerals are Associated with quartz. The commonly associated minerals are amazonite -a variety
of microcline, tourmaline, wolframite, pyrite, rutile, zeolites, fluorite, calcite, gold, muscovite, topaz,
beryl, hematite and spodumene.
4. 4
The structure of quartz is built from SiO4 tetrahedra which are linked by sharing each corner with another
tetrahedron. In a three dimensional framework, every Si has four oxygen (O) and every ‘O’ has 2 Si as
nearest neighbor. The chemical composition of quartz is nearly 100% SiO2.
Varieties of quartz
Quartz group of minerals are divided into two varieties namely:
1. Crystalline varieties.
2. Crypto crystalline varieties.
The Crystalline varieties include:
1) Amethyst
2) Milky quartz
3) Rose quartz
4) Rock crystal
5) Aventurine quartz
6) Citrine
7) Smoky quartz
8) Blue quartz
Amethyst is the beautiful Violet colored quartz crystal. The color is due to the presence of the trace
element of Ferric iron, which turns white when heated to 300°C (571°F), then to yellow (citrine) at 500°C
(932°F), but becomes violet again if exposed to x-rays or bombarded with -particles. There is a
patchyness in the color distribution of these crystals. Due to this, Amethyst is often cut as brilliant round
cuts to maximize the color effects. The color purple is traditionally the color of royalty and amethyst has
been used since the dawn of history to adorn the rich and powerful monarchs and rulers. Today, amethyst
is a lovely and affordable gemstone that is fortunately available in a wide variety of cut and uncut stones
that we can all possess and admire.
Milky quartz is another crystalline variety of quartz found in pegmatites and hydrothermal veins. The
color is generally caused by numerous bubble of gas and liquid in the crystal.
Rose quartz is one of the most desirable varieties of quartz. The rosy color of this mineral appears to be
caused by traces of manganese or titanium present in it. It occurs in massive form in many pegmatites, but
well-formed crystals are very rare. It loses its color when heated and turns black if exposed to radiation.
Rose quartz is used as an ornamental stone and as a gemstone. It is also an alternate birthstone for the
month of January. Rose quartz is associated with emotional balance and forgiveness.
Rock crystals are the most sought after crystals by mineral collectors. It is believed that the transparent,
colorless rock crystal is like a petrified ice. It occurs mainly in Pegmatites, fissures and geodes in
various rocks. It is used for optical and piezo-electrical purposes in the industries. Rock Crystal is the
name given to all clear colorless quartz. It is widely used as a popular ornamental stone and is also used
as a gemstone. Although it is one of the least expensive gemstones, cut rock crystal has been used as
imitation diamonds. Rock crystal is widely used as a gemstone due to its beauty, affordability,
availability, and ease of cutting. Rock crystal is used for many ornamental carvings from spheres (crystal
balls) to pyramids and as many forms. There are also many fine chandeliers that are outfitted with the
rock crystal ornaments.
Aventurine quartz is another variety which contains scales of mica or goethite that gives a sparkling green
or brownish-yellow appearance. It is also characterized by its translucency and the presence of platy
mineral inclusions that give a shimmering or glistening effect.
5. 5
Citrine is an Yellow or brown variety of quartz. The color is due the inclusions of colloidal iron hydrates
in it. It turns white if heated and dark brown if exposed to x-rays. It is widely used as an imitation of the
more expensive gemstone topaz. It is called as ‘Brazilian topaz’.
Smoky quartz is the light or dark brown to black variety of quartz. It is also used as a gemstone. When
heated, it turns to yellow and then to white. Smoky quartz is a popular variety of quartz. It has an
unusual color for a gemstone and is easily recognized and is well known by the general public.
Blue quartz is a variety with blue color arising due to the presence of tiny rutile, tourmaline inclusions.
These are common in metamorphic rocks.
The Cryptocrystalline varieties of quartz are those, which by nature , having a microscopic crystalline
structure. They are:
1) Agate
2) Chalcedony
3) Carnelian
4) Jasper
5) Onyx
6) Tiger’s eye
7) Rutilated quartz
8) Chrysoprase
9) Heliotrope
10) Flint or chert
Agate is a concentric, banded, fibrous variety of quartz formed by precipitation from watery solutions in
rounded cavities of volcanic rocks (geodes) . It occurs with beautiful clusters of rock crystal or amethyst
at the centre.
Chalcedony is a compact, microcrystalline variety of quartz which is usually banded. Bands of fibrous
structure alternate with microgranular bands are seen in these varieties.
Carnelian is unvaryingly colored, light to dark-brown variety of chalcedony. The orange-red color is due
to the presence of very fine particles of hematite or limonite. Traditionally used as seals.
Jasper is a massive, fine-grained quartz with large amounts of admixed material, especially iron oxides.
The commonest forms are usually strong shades of red, but grayish-green, yellow or black also occur.
Also a very common in sedimentary rocks.
Onyx is a variety of agate with alternating parallel layers of black and white lines. It also have red and
white bands. Such onyx are often employed in cameo carving.
Tiger’s eye contains fibers of crocidolite altered to a yellow color. It is a less common variety. It is
also called as “falcon’s eye”.
Rutilated quartz is a cryptocrystalline variety of quartz containing acicular yellow and red rutile crystals.
Chrysoprase is a translucent, greenish-yellow or apple-green variety which contains traces of nickel.
Heliotrope is an opaque green quartz with red markings, like drops of blood. Due to this appearance it is
called as “bloodstone”.. The red spots are caused by iron oxides.
6. 6
Flint or Chert are siliceous nodules frequently found in chalk and limestone. Flint has a compact
microcrystalline granular texture. It is dark grey to soot black in color.
Quartz is unattacked by acids other than HF.
If we look at the occurrence and crystallization of quartz, Quartz crystallizes directly from igneous
magma. Hence, it is a major constituent of plutonic, hypabyssal and volcanic rocks. It is also a common
constituent in sedimentary as well as metamorphic rocks.
As per Bowen’s reaction series, which can show how crystallization happens in a magma, quartz
crystallizes at the end, at low temperatures.
Quartz is stable under both low and high grade metamorphic conditions. Quartz is also stable in
sedimentary conditions either as detrital material or as cement in consolidated rocks. As quartz is so
common, it is impossible to enumerate all the places where it is found. It is a major constituent of sand
and soil everywhere in the world.
Uses of quartz.
Uses of Quartz in Glass Making is a primary consumption. Highly pure silica sands are used in the
glassmaking industry. Quartz sand is used in the production of container glass, flat plate glass, specialty
glass and fiberglass. Quartz is an excellent abrasive material. Quartz sands and finely ground silica sand
are used for sand blasting, scouring cleansers, grinding media, and grit for sanding and sawing.
Quartz is very resistant to both chemicals and heat. It is therefore often used as a foundry sand. With a
melting temperature higher than most metals, it can be used for the molds and cores of common foundry
work. Refractory bricks are often made of quartz sand, because of its high heat resistance.
Quartz sand is also used as a flux in the smelting of metals.
Quartz is used in the Petroleum Industry as sandy slurries in oil and gas wells. Quartz sand is used as a
filler in the manufacture of rubber, paint and putty. Screened and washed, carefully sized quartz grains are
used as filter media and roofing granules. Quartz sands are used for traction in the railroad and mining
industries. These sands are also used in recreation on golf courses, volleyball courts, baseball fields,
children's sand boxes and beaches.
High quality quartz crystals are normally single-crystal silica possessing good optical or electronic
properties that make them useful for specialty purposes. In the industries, on an average , about ten
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billion quartz crystals are used every year. Optical-grade crystals are used as lenses and windows in lasers
and other specialized devices.
"Silica stone" is an industrial term for materials such as quartzite, novaculite and other microcrystalline
quartz. These are used to produce abrasive tools, grinding stones and tube-mill liners.
Tripoli is a crystalline silica of an extremely fine grain size, may be less than ten micrometers. It is used
for a variety of “mild abrasive” purposes which include: soaps, toothpastes, metal polishing compounds,
jewelry polishing compounds and buffing compounds. Tripoli is also used in brake friction products,
fillers in enamel, plastic, paint, rubber and refractories.
Quartz minerals show a strong piezo-electric effect perpendicularly to the prism axis. Applying pressure
on a quartz crystal generates an electrical polarization along the pressure direction. Alternatively
applying an electrical tension leads to a mechanical deformation of the crystal. During the 1970s, the
"quartz watch" entered into the world market as the newest high-tech gadget. People wonder as why it
is called as a quartz watch? Or why quartz watches are so much more accurate than wind-up watches?
There is an amazing electronic phenomenon existing in the quartz crystal . Due to which it is used in the
heart of a quartz watch.
During 1970s, there was a necessity to Find a new timing element and designing an integrated circuit that
would use very little power. It was also necessary to allow the watch to run on a tiny internal battery. This
was the situation in the early 1960s. .
There was no problem with the choice of a timing element. The quartz crystal is possibly thousands of
times better for timing than the tuning fork, and quartz crystals had been around for many years.
Only the type and the frequency of the crystal needed to be chosen. The difficulty was in the selection of
the integrated circuit technology that would function at sufficiently low power.
Quartz crystals have been in regular use for many years to give an accurate frequency for all radio
transmitters, radio receivers and computers.
Their accuracy comes from an amazing set of coincidences: Quartz -- which is silicon dioxide like most
sand -- is unaffected by most solvents and remains crystalline to hundreds of degrees Fahrenheit.
The property that makes it an electronic miracle, is the fact that, when compressed or bent, it generates a
charge or voltage on its surface. This is a fairly common phenomenon called the Piezoelectric effect.
In the same way, if a voltage is applied, quartz will bend or change its shape very slightly.
If a bell were shaped by grinding a single crystal of quartz, it would ring for minutes after being tapped.
Almost no energy is lost in the material.
A quartz bell -- if shaped in the right direction to the crystalline axis -- will have an oscillating voltage on
its surface, and the rate of oscillation is unaffected by temperature.
If the surface voltage on the crystal is picked off with plated electrodes and amplified by a transistor or
integrated circuit, it can be re-applied to the bell to keep it ringing.
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The best shapes are a straight bar or a disk. A quartz bar can be tiny and oscillate at a relatively low
frequency -- 32 kilohertz (KHz). Modern quartz watches use a low-frequency bar or tuning-fork-shaped
crystal.
Often, these crystals are made from thin sheets of quartz, plated like an integrated circuit and etched
chemically to shape. Quartz is one of the most useful natural materials in the world. Its usefulness can be
linked to its unique physical properties and chemical composition.