Minerals are natural inorganic substances that make up rocks. They form through natural geological processes within the earth's crust and do not come from living things. Minerals can be identified based on their physical properties such as hardness, color, streak, luster, and cleavage or fracture pattern. Igneous rocks form as magma or lava cools and solidifies. Sedimentary rocks form through the compaction and cementation of sediments. Metamorphic rocks form from the alteration of existing rock types subjected to heat and pressure in metamorphism.

2. • A mineral is a natural inorganic substances
with a definite chemical composition.
• It is found in the earth’s crust and does not
come from living things.
• It is a naturally formed solid element or
compound in which atoms and molecules are
bound in together in a definite orderly
arrangement to form crystals.
• Most of these crystals are too small to be seen
even under a microscope.
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3. • Minerals are found in rocks.
• They appear like grains set firmly in a bed of
rock.
• Some are dark and others are light in color.
• A rock may be composed of only one kind of
mineral such as pure limestone, which is
composed of calcite.
• Others may have more than one mineral like
granite which has 3 very common minerals –
• Quartz,
• Feldspar and
• Mica.
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5. Minerals are most easily identified by their
physical properties. These are:
1. Hardness
2. Color
3. Streak
4. Luster
5. Cleavage and Fracture
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6. • Hardness is the resistance of a mineral
to scratching or abrasion. To test the
hardness of a mineral sample, scratch
it against another.
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7. • Color is one way that identification of one mineral from
another.
• It is their usually most noticeable and interesting
property.
• The outside color of the mineral may have been changed
by the atmosphere; hence, it is safe to examine the
color of a fresh surface by breaking it apart.
MICA QUARTZ GALENA
SULFUR SILVER
HEMATITE
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8. Streak refers to the color of the powder a rock or
mineral leaves behind when rubbed on a rough
surface.
The streak test consist of rubbing the mineral
against a hard surface.
The mineral hematite may be reddish
brown or brownish black when
viewed in solid form but is always
cherry red in powder form.
The color of the streak is
not always the same as the
color of the mineral.
The mineral pyrite which
has the same color as gold
leaves a greenish- black
streak while gold always
leaves a gold streak.
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9. Luster is the appearance of the surface of a
mineral in reflected light. A mineral that can
reflect much light appears very shiny.
Metals have metallic luster like silver and gold.
Nonmetals are dull such as quartz, mica or
asbestos.
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10. • Cleavage and fracture describe the way a mineral breaks.
• Any irregular break is termed a fracture while the tendency of a
certain minerals to break along one or more planes when put
under pressure is called cleavage.
• Minerals split horizontally into thin sheets.
• Feldspar splits at nearly right angles in different directions.
FELDSPAR COPPER
SULFUR SALT
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11. PETROLOGY
Studyof rocks(“petros”)
• Igneous& metamorphic
• Chiefly in the
lithosphere.
We will bedealingwith hot rocks-
Tell us about composition & history of lithosphere
origin of rocks involves:
• Transfer of heat (energy)
• Movement of material
LITHOSPHERE
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12. THINK LIKEA PETROLOGIST?
• Whatcriteria do weuseto distinguishrocks?
• Whatdo wewantto know?
• How do wemake melts?
• Whatismelted,andwhere?whatisthe role of water? how do meltsbehaveduring
solidification?
• Whatcauses metamorphism?
• How aremetamorphism&deformation related? how to rocksflow in the
interior of mountain belts?
• How do tectonic ratescompareto heatconductionrates? in whattectonic
settingsdo theserocksform?
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13. BASISFOR UNDERSTANDING
• Field methods&sample study (observation)
• Theory, experiment &modeling (analytical)
THINGS TO CONSIDER
• Materials of earth
• Physicalconditions energy
• Pressure
• Temperature & heat
• Relationship to tectonics
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14. • Igneous rock (derived from the Latin word ignis meaning fire),
or magmatic rock, is one of the three main rock types, the
others being sedimentaryand metamorphic.
• Igneous rock is formed through the cooling and solidification
of magma or lava.
• The magma can be derived from partial melts of existing rocks
in either a planet's mantle or crust.
• Typically, the melting is caused by one or more of three
processes: an increase in temperature, a decrease in pressure,
or a change in composition.
• Solidification into rock occurs either below the surface
as intrusive rocks or on the surface as extrusive rocks.
• Igneous rock may form with crystallization to form granular,
crystalline rocks, or without crystallization to form natural
glasses.
Igneous rock
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16. Igneous and metamorphic rocks make up 90–95% of the
top 16 km of the Earth's crust by volume.
Igneous rocks are also geologically important
because:
• Their minerals and global chemistry give information about
the composition of the mantle, from which some igneous
rocks are extracted, and the temperature and pressure
conditions that allowed this extraction, and/or of other pre-
existing rock that melted;
• Their absolute ages can be obtained from various forms
of radiometric dating and thus can be compared to adjacent
geological strata, allowing a time sequence of events;
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17. • Sedimentary rocks are types of rock that are formed by
the deposition and subsequent cementation of that
material at the Earth's surface and within bodies of water.
• Sedimentation is the collective name for processes that
cause mineral or organic particles (detritus) to settle in
place.
• The particles that form a sedimentary rock by
accumulating are called sediment.
• Before being deposited, the sediment was formed
by weathering and erosion from the source area, and then
transported to the place of deposition
by water, wind, ice, mass movement or glaciers, which are
called agents of denudation.
• Sedimentation may also occur as minerals precipitate
from water solution or shells of aquatic creatures settle out
of suspension.
Sedimentary rocks
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19. Clastic sedimentary rocks are composed of other rock fragments that were
cemented by silicate minerals.
Biochemical sedimentary rocks Biochemical sedimentary rocks are
created when organisms use materials dissolved in air or water to build their
tissue.
Examples include:
Most types of limestone are formed from the calcareous skeletons of organisms
such as corals, mollusks, and foraminifera.
Coal, formed from plants that have removed carbon from the atmosphere and
combined it with other elements to build their tissue.
Chemical sedimentary rocks
Chemical sedimentary rock forms when mineral constituents
in solution become supersaturated and inorganically precipitate. Common
chemical sedimentary rocks include oolitic limestone and rocks composed
of evaporite minerals, such as halite (rock salt), sylvite, barite and gypsum
"Other" sedimentary rocks This fourth miscellaneous category includes
rocks formed by Pyroclastic flows, impact breccias, volcanic breccias, and other
relatively uncommon processes.
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20. Metamorphic rocks arise from the transformation of
existing rock types, in a process called metamorphism, which means
"change in form".
• The original rock (protolithic) is subjected to heat
(temperatures greater than 150 to 200 °C.
• Metamorphic rocks make up a large part of the Earth's
crust and form 12% of the Earth's land surface.
• They are classified by texture and
by chemical and mineral assemblage (metamorphic facies).
• The study of metamorphic rocks (now exposed at the
Earth's surface following erosion and uplift) provides
information about the temperatures and pressures that
occur at great depths within the Earth's crust.
• Some examples of metamorphic rocks
are gneiss, slate, marble, schist, and quartzite.
Metamorphic rocks
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22. Metamorphic minerals
• Metamorphic minerals are those that form only at the high
temperatures and pressures associated with the process of
metamorphism.
• These minerals, known as index minerals,
include sillimanite, kyanite, staurolite, andalusite, and some garnet.
• These minerals formed during the crystallization of igneous rocks.
• They are stable at high temperatures and pressures and may remain
chemically unchanged during the metamorphic process.
• However, all minerals are stable only within certain limits, and the
presence of some minerals in metamorphic rocks indicates the
approximate temperatures and pressures at which they formed.
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23. Foliation
• The layering within metamorphic rocks is called foliation (derived
from the Latin word folia, meaning "leaves"), and it occurs when
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24. Types of metamorphism
Contact metamorphism
• Contact metamorphism is the name given to the changes that take place
when magma is injected into the surrounding solid rock (country rock).
• The changes that occur are greatest wherever the magma comes into
contact with the rock because the temperatures are highest at this
boundary and decrease with distance from it.
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25. Regional metamorphism
• Regional metamorphism, also known as dynamic metamorphism, is the name
given to changes in great masses of rock over a wide area.
• Rocks can be metamorphosed simply by being at great depths below the Earth's
surface, subjected to high temperatures and the great pressure caused by the
immense weight of the rock layers above.
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26. Metamorphic rock textures
• The five basic metamorphic textures with typical rock types are
• Slaty (Includes slate and phyllite; the foliation is called "slaty cleavage"),
• Schistose (Includes schist; The foliation is called "schistosity"),
• Gneissose (Gneiss; the foliation is called "gneissosity"),
• Granoblastic (Includes granulite, some marbles and quartzite), and
• Hornfelsic (Includes hornfels and skarn).
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