This document discusses different types of rocks, focusing on igneous rocks. It defines igneous rocks as those formed by the cooling and solidification of magma or lava. Igneous rocks are classified based on where they form (intrusive or extrusive) and their mineral composition. Intrusive igneous rocks form underground and have larger crystals, while extrusive rocks form above ground and have smaller crystals. The document describes four textures of igneous rocks: glassy, fine-grained, coarse-grained, and porphyritic. Examples of different igneous rock types are provided.

2. PRESENTATION
•Topic: Rocks
•Sharafat Hussain
L- 14ce08
QUCEST LARAKANA

3. • A rock is a naturally occurring
solid mixture of one or more
minerals, or organic matter
• Rocks are classified by how
they are formed, their
composition, and texture
• Rocks change over time
through the rock cycle
What are Rocks?

4. Igneous Rock
• Igneous rocks
form when molten
rock cools and
solidifies. Molten
rock is called
magma when it is
below the Earth’s
surface and lava
when it is above.

5. Igneous Rock
classification
• Igneous rocks are classified two
different ways:
– Where they were formed
– What they are made from (mineral
composition)

6. Intrusive Igneous Rocks
• Igneous rocks that form
below the Earth’s surface
are called intrusive igneous
rocks (or plutonic).
• The word “plutonic” comes
from Pluto.
• They form when magma
enters a pocket or chamber
underground that is
relatively cool and solidifies
into crystals as it cools very
slowly.

7. Intrusive Igneous Rock
• Most intrusive rocks have
large, well formed
crystals. The mineral
crystals within them are
large enough to see
without a microscope.
• The more slowly molten
rock cools within the
Earth, the larger the
igneous rocks crystals will
be.
• Examples of intrusive
igneous rocks are granite,
gabbro and diorite
GraniteGabbroDiorite

8. Extrusive Igneous Rocks
• Extrusive igneous rocks, or
volcanic, form when magma
makes its way to Earth's
surface. The molten rock
erupts or flows above the
surface as lava, and then
cools forming rock.
• Most extrusive (volcanic)
rocks have small crystals.
Examples include basalt,
rhyolite, etc.

9. Igneous Rock Textures
Igneous rocks have four
basic types of textures:
glassy, fine-grained, coarse-
grained and porphyritic

10. Glassy Igneous
Glassy igneous
rocks are shiny
and look like
glass. The
minerals that
make up a glassy
igneous rock are
not organized into
crystals.
Obsidian has a
glassy texture.

11. Fine-Grained Igneous
• Fine-grained rocks,
unlike glassy rocks,
are made of
interlocking mineral
crystals. These
crystals are too small
to be seen without
the help of a
microscope. The dark
gray rock known as
basalt has a fine-
grained texture.

12. Coarse-Grained Rock
• Coarse-grained
rocks, such as
granite, consist of
interlocking
mineral crystals,
which are all
roughly the same
size and visible to
the unaided eye.

13. Porphyritic Igneous Rocks
• Porphyritic rocks
consist of large
crystals scattered on
a background of much
smaller crystals.
Sometimes these small
background crystals
are too tiny to be seen
with a microscope.
Porphyritic rocks have
a texture that
resembles rocky road
ice cream.

15. 2. BASALT

16. 3.GABBRO

17. 4.GRANITE-COARSE GRAINED

18. 5.OBSIDIAN

19. 6.PEGMATITE

20. 7.PERIDOTITE

21. 8.QUARTZ- DIORITE

22. 9. PUMICE

23. 10. RHYOLITE

24. 11. SCORIA

25. 12. WELDED- TUFF