2. Rock- is a naturally-occuring aggregate or
combination of minerals.
Petrology- is the scientific study of rocks.
Petrologist- is a person(geologist) who
specializes in petrology.
Classification of Rock
1. Igneous rocks
2. Sedimentary rocks
3. Metamorphic rocks
3. Igneous rocks- formed from hardening and
crystallization of magma or molten mineral.
Types of Igneous rocks
1.Extrusive/Volcanic- lava that cools rock
-fine grained crystals since the cooling process
is so fast.
-e.g basalt and andesite
2.Intrusive/Plutonic- magma that cools slowly
-coarse grained crystals.
- e.g granite, diorite and syenite
4. Classification based on Composition
i. Felsic- light color feldspar, silicate
ii. Mafic- dark in color, made up of
magnesium and iron
iii. Intermediate- between mafic and felsic
iv. Ultramafic- very dark
5. Based on Texture
i. Aphanistic- fine grained
ii. Phanetiric- coarse grained
iii. Porphyritic- large crystals with small
crystals
iv. Glassy- non-ordered solid from rapid
quenching
v. Pyroclastic –composite of ejected
fragments
6. Sedimentary rocks- formed from
preexisting rocks.
Types of Sedimentary rocks
1. Clastic- formed from accumulation of clasts
little pieces of broken rocks and shells.
2. Chemical- formed when dissolved minerals
precipitate from a solution.
3. Organic- formed from the accumulation of
materials from living things .livin
7. Metamorphic-formed from pre-existing
rocks, there rocks have been modified by
heat, pressure and chemical processes.
Metamorphism- change of minerals or
geologic texture in pre-existing
rocks(protolith) without the protolith
melting into liquid magma(solid state
change )
8. Two types of metamorphism
1. Regional- happens over large region of the
crust where high Temperature and Pressure
is present
2. Contact- happens on layers of rocks having
contact with heat magma
