Rocks and its types

1. ROCKS
• Minerals aggregate that make up the earth crust.
• Natural complexes bodies that are composed of
minerals.
• Single mineral rocks e.g., rock salt or more than
two minerals rocks e.g., granite, sandstone etc.
Minerals are naturally complexes bodies
composed of separate chemical elements e.g.,
feldspar, mica, quartz.

2. Rocks
Igneous rocks
Sedimentary
rocks
Metamorphic
rocks

3. Igneous rocks
• Magma.
• The product of cooling, segregation and
crystallization of magma.
• Magma originates more than 200 km depth in
the interior of the earth consists of mixture of
oxides and silicates.
• The rock properties depends on:
• Position of the cooling magnetic bodies.
• Conditions of the pressure and temperature.
• Magma composition and its cooling rate.

4. Igneous
rocks
Volcanic or Effusive
or Extrusive
(Lava)
e.g., Felsites, Basalt
Plutonic or Intrusive
(Magma)
e.g., Granite

5. Sedimentary rocks
• Formed by sediments/sedimentation.
• Sediments.
• Upper most part of the earth crust and
occupy an enormous area (70%).
• Formed in marine basins and on the
surface of land by 3 process (1 ft/900
years):
• Accumulation.
• Chemical precipitation.
• Life activity of organisms.

6. Sedimentation
• Detritus material comprising rocks and minerals.
• Rivers, oceans, winds and rain all have ability to
carry the particles washed off of eroding rocks.
• When the energy is not strong enough to carry
these particles, the particles drop out in the
process of sedimentation.

7. • Sedimentation occurs by 3 process:
– Transportation
• Sliding down slopes
• Wind
• Running water
– Deposition
• Sediment is deposited when the energy of
transporting medium becomes too low to continue
the transport process.
– Diagenesis
• Compaction
• Cementation
• Recrystallization

8. Sedimentary
Rocks
Clastic
sedimentary
rocks
Chemical
sedimentary
rocks
Biogenic
sedimentary
rocks

9. Clastic Sedimentary Rocks
• Formed by the destruction of other rocks.
• Grouped by size e.g.:
– Gravel (boulder+cobble+pebble).
– Sandstone (sand).
– Mudstone, shale (silt).
– Claystone (clay).

10. Chemical Sedimentary Rocks
• Non clastic rocks.
• Components are formed by chemical
agencies from material in solution e.g.:
– Calcite (CaCo3), predominate.
– Chert (chemically precipitated SiO2).
– Evaporites (salt and gypsum).

11. Biogenic Sedimentary Rocks
• Formed by biological agencies e.g.:
– Limestone (calcite precipitated by marine
organisms).
– Diatomite (siliceous ooze).
– Coal (accumulation of dead plant matter in a
reducing environment).
– Oil shale (high abundance of organic matter
that is converted to petroleum during
diagenesis).

12. • The product of
alteration of
other rocks.
• Metamorphism.
Metamorphic
Rocks
Contact
metamorphism
Regional
metamorphism
Dynamic
metamorphism
Examples:
Sandstone » quartzite
Limestone » marble