1. Classification based upon formation
Rock types
Classification based upon formation

2. Igneous rocks form from molten lava.
What’s the difference between magma and lava?
The formation of igneous rocks is destructive because old rocks are melted and constructive because new rocks are formed.

3. Igneous rocks
When magma cools slowly while still under ground, the minerals in the rock have time to form crystals. Those crystals make intrusive igneous rocks have a coarse grain with visibly mottled coloration.
Granite is a coarse grained intrusive rock made mostly of quartz

4. Other intrusive igneous rocks
Peridotite is a coarse-grained
igneous rock made mostly of
olivine
Diorite is a coarse grained
igneous rock made mostly
of feldspar

5. EXTRUSIVE IGNEOUS ROCKS
When lava cools on the Earth’s surface, there is little time for crystals to form, so extrusive igneous rocks lack the coarse grain typical of intrusive igneous rocks.
Basalt is a fine-grained extrusive igneous rock, which happens to be
the most common rock on Earth. It is susceptible to chemical
weathering, where it breaks down to form clay.

6. Extrusive igneous rocks
Obsidian is volcanic glass which cools so rapidly that not even the finest crystals can form.

7. extrusive Igneous Rocks
Scoria is another igneous rock filled with vesicles – the proper term for the gas bubbles in these rocks.
Pumice cools so quickly and with so
many gas bubbles that it can float.

8. Metamorphic Rocks
Metamorphic rocks have been modified by heat, pressure and chemical process usually while buried deep below Earth's surface. Exposure to these extreme conditions has altered the mineralogy, texture and chemical composition of the rocks.
Marble is an nonfoliated metamorphic rock which forms when limestone is exposed to great heat and pressure.

9. Metamorphic rocks
Both slate (below) and gneiss (at right)
are examples of foliated metamorphic
rocks .
Foliated metamorphic rocks have obvious layers and often split into thin sheets.

10. Sedimentary Rocks
Sedimentary rocks form from the accumulation of sediments, often but not always at the bottom of a body of water. Sedimentary rocks are divided into three major groups: clastic, chemical, and organic.
Conglomerate is a clastic sedimentary rock,
which means it forms as a result of mechanical
weathering.

11. Clastic Sedimentary rocks
Sandstone and shale are both clastic sedimentary rocks. Sandstone is made of compressed particles of sand, and shale is made of smaller particles of clay or mud.

12. Halite is rock salt which forms when
Chemical Sedimentary
Halite is rock salt which forms when
bodies of salt water evaporate, leaving
their salt content behind.
Hematite is iron ore that formed when
the iron and oxygen in bodies of water
chemically reacted and settled to the sea floor.

13. Organic Sedimentary Rocks
Coal forms from the remains of decayed
plant matter in swampy environments.
Limestone forms from the accumulation of
calcium-rich shells, coral and other detritus
of marine life

14. How is the water cycle vital to the formation of sedimentary rocks?
In what ways is the formation of sedimentary rocks both constructive and destructive?
How is the water cycle vital to the formation of sedimentary rocks?