Igneous rocks are formed by the cooling or solidification of magma or lava. Sedimentary rocks are formed by the compaction and cementation of sediments, a process called lithification. Metamorphic rocks are formed by preexisting rocks that are exposed to extreme heat and pressure in the Earth’s interior, a process called metamorphism.

1. CLASSIFICATION OF
ROCKS

2.  Igneous rocks are formed by the cooling or
solidification of magma or lava.
 Sedimentary rocks are formed by the
compaction and cementation of sediments, a
process called lithification.
 Metamorphic rocks are formed by preexisting
rocks that are exposed to extreme heat and
pressure in the
Earth’s interior, a process called metamorphism.

3. A. Igneous Rocks

5. Intrusive rocks – (or plutonic rocks) are igneous
rocks formed underneath the earth. They are
coarse-grained due to the slow cooling of magma
allowing crystal growth
Extrusive rocks – (or volcanic rocks) are igneous
rocks formed on the surface of the earth. They are
cooled lava, which are molten rocks ejected on the
surface through volcanic eruptions. They are fine-
grained due to abrupt cooling on the surface.

6. Rock Name Colour Texture
Diorite medium
coloured
course
Rhyolite light coloured
(pastel)
pastel
Obsidian dark coloured glass
Tuff fine-grained ash ash particles
Igneous Rocks Examples
This section will discuss the various examples of igneous rocks and
their uses.
Granite
Basalt
Pumice
Other examples of igneous rocks along with their features are listed
below in the table:

7. Sedimentary Rocks

8. Sedimentary Rocks
• Clastic sedimentary rocks – are made up of sediments
from preexisting rocks. When preexisting rocks are
physically weathered and eroded, they form
sediments. When these sediments are transported,
deposited, and lithified, they form the clastic
sedimentary rocks. These rocks can be identified
based on their grain size.
• Non-clastic sedimentary rocks – can be biological,
chemical, or a combination of both.
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9.  Chemical sedimentary rocks are from chemical
precipitation (e.g. rock salt formed when dissolved
salts precipitate from a solution).
 Biological sedimentary rocks are lithified
accumulation of dead organisms (e.g. coal formed
from carbon-rich plants and limestone from the
remains of calcareous organisms).

11. Metamorphic Rocks
 Foliated metamorphic rocks – have layered or
banded appearance produced by exposure to high
pressures. (e.g. slate, phyllite, schist, and gneiss);
formed through regional metamorphism (pressure)
 Non-foliated metamorphic rocks – do not have
layered appearance. (e.g. marble, quartzite, and
anthracite); formed through contact metamorphism
(heat)

12. THE ROCK CYCLE

14. pressure Biological matter lava cools quickly
clastic May be vesicular compacted sediments
Extrusive classified by size contains air bubbles
Rocks large crystals form small or no crystals forms
Heat Evaporates magma cools slowly
Contact Metamorphic classified on how they are formed
Intrusive Building blocks of Forms from cooling and solidification of lava or magma
Mineral Non-clastic rocks change due to temperature and/or pressure change
igneous regional Generally forms from the compaction and sedimentation of sediments

15. Building blocks of
Rocks
intrusive
may be vesicular
Compacted sediments
Non - clastic
evaporites