This document discusses the physical, chemical properties and structure of common rock-forming minerals. It describes key properties such as color, streak, hardness, cleavage and provides examples for common silicate minerals including feldspar, mica and quartz. It explains how these minerals can be identified using physical and chemical tests and outlines their typical crystal structures and common occurrences in different rock types.

1. PHYSICAL, CHEMICAL PROPERTIES AND
STRUCTURE OF MINERALS
BY
SYED NAWAZ
M-TECH 1ST SEM
PETROLEUM EXPLORATION AND PRODUCTION
DELTA STUDIES INSTITUTE, ANDHRA UNIVERSITY
11/11/2019 1

2. CONTENT
• INTRODUCTION
• Physical Properties
• Chemical Properties
• Minerals
• FELSPAR
• MICA
• QUARTZ

3. INTRODUCTION
• A MINERAL IS A NATURALLY OCCURING HOMOGENEOUS SUBSTANCE
WHICH HAS A MORE OR LESS DEFINITE CHEMICAL COMPOSITION
AND DEFINITE ATOMIC STRUCTURE
• MINERALS ARE DIVIDED INTO 2 TYPES:
• ROCK-FORMING MINERALS: ARE THOSE WHICH ARE FOUND IN ABUNDANCE
IN THE ROCK OF THE EARTH’S CRUST
• ORE-FORMING MINERALS: ARE THOSE WHICH ARE OF ECONOMIC VALUE BUT
DO NOT OCCUR IN ABUNDANCE IN ROCKS.
• ONLY 29 MINERALS ARE COMMON IN ROCKS AMONG WHICH ONLY 8
ELEMENTS COMPOSE THE BULK OF THESE MINERALS AND ABOUT
98% OF THE CONTINENTAL CRUST.

4. 8 ELEMENTS ARE
• OXYGEN
• SILICON
• ALUMINIUM
• IRON
• CALCIUM
• POTASSIUM
• SODIUM
• MAGNESIUM
• OUT OF THESE, 2 MOST
ABUNDANT ELEMENTS ARE
SILICON AND OXYGEN WHICH
COMBINE TO FORM THE
MINERAL GROUP KNOWN AS
SILICATES

5. The mineral which in common rocks are
divided as
S.No Mineral Group Examples
1 Oxides Quartz, Magnetite, Hematite, Limonite, etc
2 Silicates Felspa, Mica, Hornblende, Augite, Olivines, Etc
3 Carbonates Calcite, Dolomite, Siderite, etc
4 Sulfides Pyrite, Galena, Sphalerite, etc
5 Sulfates Gypsum,etc
6 Chlorites Rock salt, etc
These minerals can be identified with physical,
chemical properties and their structure

6. PHYSICAL PROPERTIES
• THE PHYSICAL PROPERTIES OF MINERALS CAN BE DETERMINED BY SIMPLE TESTS.
• BECAUSE OF THIS WE CAN GET AN OVERVIEW OF THE MINERALS APART FROM ITS CHEMICAL PROPERTY.
• SOME OF THE IMPORTANT PHYSICAL PROPERTIES:
S.No Physical Property S.No Physical Property
1- Colour 2- Streak
3- Lustre 4- Hardness
5- Habit 6- Cleavage
7- Odor 8- Feel
9- Fracture 10- Tenacity
11- Fluorescence 12- Phosphorescence
13- Magnetism 14- Specific Gravity

7. Colour
• Colour of a mineral is due to absorption of certain wavelength of light by
atoms making up the crystal
• The remaining wavelengths of white light that are not absorbed give rise to
the colour and this can be observer.
• Thus dark coloured minerals absorb most of the light whereas red minerals
reflect or transmit mainly the red light and absorb all others.
• Constant colour, Eg.
• lead grey of galena,
• brass-yellow of pyrite and
• green of chlorine.
• In other cases, the colour is variable such as quartz

8. Lead grey of galena brass-yellow of pyrite green of chlorine

9. • Presence of small amounts of impurities can give a variety of colours
to a white of colourless minerals.
• For example, the colour of amethyst and rose-quartz is die to the
presence of titanium of manganese in traces.
• The most common colouring impurity is hematite.
• The term opalescence is applied to minerals which show milky
appearance.

10. Streak
• The colour of the mineral powder is called streak . It is more
consistent and reliable than the body colour of the minerals.
• The streak is obtained by rubbing a mineral against the streak plate.
• For example, hematite which appears almost black, gives a red
coloured streak.
• However the streak is less useful for identifying most of the silicates,
carbonates, and transparent minerals because they give white streak.

11. Hematite
Gypsum
FluoriteCalcite
Pyrite

12. Lustre
• It is a measure of the reflectivity of the mineral surface.
or
• How mineral shine under reflection of light
S.No Type Definition
1 Metallic lustre Minerals which have the appearance of a metal, also to hace a metallic
lustre Eg. Pyrite and galena
2 Submetallic lustre The weakly displayed metallic lustre is called submetallic lustre. Eg.
Chromite and hematite
3 Vitreous lustre It is the lustre exhibited by the broken glass Eg. quartz
4 Adamantine A hard brilliant lustre like that of a diamond, is called adamantine lustre.
It is due to the minerals high index of refraction Eg. Transparent
cerussite
5 Pearly lustre It is the lustre exhibited by the pearls Eg. Muscovite, calcite
6 Silky Lustre It is the lustre exhibited by the silk fibres. Minerals which crystallize in
fibrous habit commonly show silky lustre E. asbestos and fibrous gypsum

13. pyrite

14. Hardness
• It is one of most useful diagnostic properties of a mineral. It is defined
as the resistance of a mineral to abrasion or scratching.
• hardness is determined by rubbing a mineral of unknown hardness
against one of known hardness
• A numerical value is obtained by using the mohs scale of hardness.
• In the absence of hardness testing minerals, the following materials
may be used to determine approximate hardness.
• A finger glass will scratch upto about 2.5

15. Mohs scale
Hardness Mineral Remarks
1 Tale Scratched by a finger nail
2 Gypsum
3 Calcite
Scratched by a knife4 Fluorite
5 Apatite
6 Orthoclase
Scarcely scratched by a knife7 Quartz
8 Topaz
Not scratched by a knife9 Corundum
10 Diamond

17. Habit
• The habit of a mineral can be defined as the size and shape of the
crystals.
S.No Habit Type Definition
1 Accicular Needle like crystal
2 Fibrous Aggregate of long thin fibre
3 Foliated Foliated Aggregate of thin separable sheets
4 Bladed Small knife blade
5 Tabular Broad Flat surface
6 Columnar Columnar crystal
7 Botryoidal Rounded masses like bunch of grapes
8 Reniform Kidney shape
9 Granular Aggregate of equidimensional grains
10 Pisolitic Rounded grains of pea size
11 Oolitic Fish eggs
12 Massive Structureless mass

18. Granular Botryoidal
Columnar

19. Cleavage
• The tendency of a mineral to break along flat planar surfaces
• Cleavage can have 1, 2, or 3(multi directions)
• More over cleavage is the property which is related to the atomic
arrangement within the mineral and it always occur parallel to possible
crystal face
• Classified as
• Perfect
• Good
• Poor
• Indistinct
• Classified on the basis of
• How easy can crystal cleaves
• How perfect the shape is

21. Fracture
• Minerals which do not exhibit cleavage, break with an irregular
surface.
• The nature of this broken surface is called fracture.
• The direction of the fracture is in a direction other then cleavage.
• Fracture do not produce smooth surface. The types of fractures are:
S.No Fracture type Definition
1 Conchoidal Curved fracture surface showing concentric
lines like a shell.
2 Even Surface is almost flat
3 Uneven Surface is irregular and rough
4 Hackly Surface is rough with sharp and jagged points.

22. Conchoidal fracture
UnEven fracture
Even fracture
Hackly fracture
Pyrite has
Conchoidal fracture

23. Odor
• Smell and the type of odors are
S.No Type Definition
1 Arsenical Odor is garlic
2 Sulfurous Burning sulfur Pyrite gives this type odor
3 argillaceous Odor is like clay

24. Feel
• Is the sensation upon touching or handling minerals.
• The different type of feel are
• Greasy
• Soapy
• Rough
• Harsh

25. Tenacity
• Tenacity means how easily can break
• Classified as
• Sectile: can be cut with knife but slices are not malleable
• Malleable: minerals which flatten under the hammer
• Flexible: can be bent
• Elastic minerals which spring back after bending
• Brittle: can be easily break
• Friable: can be powdered easily
• Pulverulent: mineral which are powdery and have little or nor cohesive

26. flourescence
• Minerals when exposed in sunlight or UV light, produce a colour quite
different from their own.
• Thus green or colourless fluorite turns to blue or purple.

27. Phosphorescence
• Some minerals glow and emit light when they are placed in UV light
• The glow induced in the mineral may continue for some time even
after a removal of external source (UV light).
• This property of mineral is called phosphorescence.

28. Magnetism
• Minerals attracted by a magnet

29. Specific gravity
• It shows how dense the mineral is. In comparison with water.
• Methods used for the determination
• Direct calculation (theoretical appraoch)
• Walker’s steel yard
• Jolly’s spring balance

30. Chemical properties of minerals
• Each minerals has a crystalline structure and almost a definite
chemical composition.
• Chemical properties of minerals show the presence and arrangement
of atoms in minerals
• Based on chemical properties, can identify their reactivity with other
substances.
• The properties which are directly related to the chemical composition
of minerals are
• isomorphism,
• polymorphism and
• pseudomorphism

31. Isomorphism
• When variations in chemical composition take place in any one
mineral, the phenomenon is called “Isomorphism”
• A group of minerals related to each other in this manner form an
Isomorphus series.
• These minerals show a continuous variation in their chemical
composition but their crystal structure remain almost same.
• The plagioclase felspars which are a group of triclinic minerals provide
an examples

32. Polymorphism
• The ability of a specific chemical compound to crystallize with more
than one type of structure, is known as polymorphism.
• In this case, each crystal form gives rise to a separate minerals
species.
• Such minerals which have identical chemical composition but
different atomic structure are called polymorphs
• Polymorphs of carbon are graphite and diamond and of caco3 are
calcite and aragonite

33. Pseudomorphism
• If a minerals exists with the outward form of another mineral species
the phenomenon is called pseudomorphism
• Mineral pseudomorphs are found when one mineral is replaced by
another without any change in the outer form of the original mineral.
• Thus the chemical composition and structure of a pseudomorph
belongs to one mineral species whereas the crystal form correspond
to another
• Quartz (SiO2) after fluorite (CaF2)

34. Introduction
• Silicate minerals are by far the most common rockforming minerals.
• They constitute about 95% of the earth’s crust.
• The important silicate minerals are Felspar, Quartz, Mica, Aluminium
etc.,

35. FELSPAR GROUP
• THE FELSPAR ARE THE MOST ABUNDANT OF ALL MINERALS. THEY FALL INTO 2 MAIN
SERIES.
• K-NA FELSPARS, CALLED THE ALKALI FELSPARS
• CA-NA FELSPARS, CALLED PLAGIOCLASE FELSPARS
• ALL FELSPAR SHOW CLOSELY RELATED PHYSICAL PROPERTIES.
• CLEAVAGE-GOOD IN 2 DIRECTIONS AT AN ANGLE OF 90 DEGREES APPROXIMATELY.
• HARDNESS – 6
• SPECIFIC GRAVITY – 2.55-2.63
• LUSTER – VITREOUS
• COLOUR - WHITE, GREY, PINK OR GREEN
• HABIT – GENERALLY TABULAR
• USE – IN THE MANUFACTURE OF PROCELAIN

36. • The general formula for the
feldspars is XAL(ALSI)Si2O2
• Where X can be potassium,
sodium, calcium or barium.
• 1 angstrom = 10^(-10) metres
• Mainly used to express the
interatomic distances

37. OCCURRENCE
• THE ALKALI FELSPARS WHICH INCLUDE ORTHOCLASE, MICROCLINE
AND ALBITE, HAVE A SIMILAR OCCURRENCE. THEY ARE COMMONLY
FOUND IN IGNEOUS ROCKS, SUCH AS GRANITES, PEGMATITES,
SYENITES, RHYOLITES AND TRACHYTES.
• OLIGOCLASE IS COMMONLY FOUND IN GRANODIORITES AND
ZONITES
• LABRADORITE IS A COMMON CONSTITUENT OF GABBROS, BASALTS
AND ANORTHOSITES

38. MICA
• Chemical formula : Sio2
• Crystal system – monoclinic
• Cleavage – perfect basal
• Hardness 2-2.5
• Specific gravity – 2.76-2.88
• Luster – pearly or silky
• Colour – colourless, pale, shade green and brown, transparent in thin
sheets
• Habit – usually tabular crystals, foliated

40. OCCURRENCE
• MUSCOVITE IS A CHARACTERSTIC MINERAL OF GRANITES AND
GRANITE-PEGMATITE.
• IN PEGMATITES LARGE CRYSTAL OF MUSCOVITE ARE FOUND.
• MUSCOVIT IS ALSO COMMON IS SCHISTS AND GNEISSES.

41. USES
• MUSCOVITE IS WIDELY USED FOR INSULATION AS A DIELECTRIC IN
ELECTRICAL INDUSTRY.
• GROUND MICA IS USED AS A FILLER.
• MUSCOVITE IS ALSO USED FOR HEAR RESISTANT SUPPORTS AND
WINDOWS.

42. QUARTZ : SIO2
• CRYSTAL SYSTEM HEXAGONAL
• CLEAVAGE – ABSENT
• HARDNESS – 7
• SPECIFIC GRAVITY – 2.65
• FRACTURE – CONCHOIDAL
• LUSTER – VIREOUS
• COLOUR – COLOURLESS, WHITE OR WITH A WIDE RANGE OF TINTS
• HABIT – PRISMATIC CRYSTALS OR MASSIVE

43. IMPORTANT VARITIES OF QUARTZ
• ROCK CRYSTAL – COLOURLESS QUARTZ, COMMONLY IN DISTINCT
CRYSTALS.
• AMETHYST – TRANSPARENT QUARTZ WITH PURPLE COLOUR
• SMOKY QUARTZ – COLOUR IN SHADES OF GREY OR BROWN
• ROSE QUARTZ – COLOUR A RED ROSE OR PINK
• MILKY QUARTZ – COLOUR MILKY WHITE

44. CRYPTOCRYSTALLINE FORMS OF QUARTZ
• CHALCEDONY – WAXY LUSTRE AND BOTRYOIDAL FROM
• AGATE – A BANDED VARIETY WITH LAYERS OF CHALCEDONY HAVING
DIFFERENT COLOUR
• JASPER – RED CHALCEDONY STAINED BY HENATITE
• FLINT - DARK GRAY SILICEOUS NODULES
• CHERT – LIGHT COLOURED MASSIVE QUARTZ
• OPAL – AN AMORPHOUS VARIETY OF QUARTZ (SIO2.NH2O)

45. OCCURRENCE
• QUARTZ OCCURS IN MOST IGNEOUS, METAMORPHIC AND
SEDIMENTARY ROCKS
• SOME SANDSTONES AND QUARTZITES ARE COMPARED ALMOST
ENTIRELY OF QUARTZ
• IT IS ALSO FOUND ABUNDANTLY AS A GANGUE MINERAL IN MINERAL
VEINS.
• AGATE OCCURS IN VOLCANIC LAVAS AS CAVITY FILLING

46. USES
• COLOURED VARIETIES ARE USED AS SEMIPRECIOUS STONE
• IN THE FORM OF SAND IT IS USED AS CONSTRUCTION MATERIAL
• QUARTZ IS USED AS A FLUX OR ABRASIVE IN INDUSTRIES
• QUARTZ CRYSTALS ARE USED AS OSCILLATORS IN ELECTRICAL
EQUIPMENTS, SUCH AS WATCHES.

47. ?