TYPES OF ROCKS

TYPES OF ROCKS

• Igneous
• Metamorphic
• Sedimentary

WHAT IS A ROCK?

HOW ARE ROCKS CLASSIFIED?

• Mineral composition» the minerals and organic matter a rock contains
• Texture» the size, shape, and positions of the grains that make up a rock

IGNEOUS ROCKS

HOW DO IGNEOUS ROCKS FORM?

• They form when hot, liquid magma cools into solid rock

WHAT ARE THE TWO TYPES OF IGNEOUS ROCK?

• Intrusive» Magma that doesn't reach earth's surface, and cools inbetween layers of surrounding rock. They usually have a course-grained texture like granite, and diorite.
• Extrusive» Forms when lava erupts onto earth's surface. It cools very quickly so there is very little time for crystals to form so they are usually fine-grained. Basalt and andesite are common extrusive igneous rocks.

SEDIMENTARY ROCKs

HOW DO SEDIMENTARY ROCKS FORM

• They form from weathering, erosion, burial, and cementation

WHAT ARE THE THREE TYPES OF SEDIMENTARY ROCK?

• Clastic» forms when sediments are buried, compacted, and cemented together by calcite or Quartz
• Chemical» form when water evaporates, like halite
• Organic» forms from the remains or fossils, of once-living plants and animals, like coquina or coal

METAMORPHIC ROCKS

HOW dO METAMORPHIC ROCKS FORM?

• When a rock is exposed to high temperature and pressure, the rocks change to form new minerals

WHAT ARE THE TWO TYPES OF METAMORPHIC ROCKS?

• Foliated» pressure causes the mineral grains in a rock to realign to form parallel bands, like slate or schist
• Nonfoliated» usually made of one or only a few minerals. They change size or shape to form nonfoliated metamorphic rocks, like quartzite or marble.