IGNEOUS ROCK

Intrusive: rocks cool down in the earth, slowly, and form large crystals

Extrusive: rocks rise up to the surface and cool down quickly, and created small crystals

TEXTURES

Phaneritic: coarse grained, slow cooling

Porphyritic(course-grained ground masses): slow then fast cooling

Pegmititic: slow cooling, high water content

Aphanitic: fine grained, fast cooling

Porphyritic(fine grained ground masses): slow then fast cooling

Glassy: Fast cooling, high silica content

COMPOSITION

Igneous rock can be classified by the amount of mineral in the rock and the general chemical makeup. Ultramafic: olivine, pyroxene

Mafic: plagioclase, pyroxene

Felsic: feldspar, > 10% quartz, < 15% mafic material

Intermediate: felsic and mafic materials, little quartz

TYPES OF IGNEOUS ROCK

Andesite: extrusive, aphanitic to porphyritic, intermediate composition

Granite: intrusive, porphyritic, felsic

Rhyolite: extrusive, felsic, glassy to aphanitic to porphyritic

SEDIMENTARY

Sedimentary rocks are formed when loose sediment is compacted over time. This creates layers, and the act of layers turning to rock is called lithification.

Sedimentary rocks are created by weathering, then the broken rock is transported and evened out on the ground. Over time, different types of rocks layer and compact, and then eventually are cemented into one rock.

CLASSIFICATION

Clastic rocks are formed by weathering. Sandstone and slate are clastic. Chemical rocks are formed by being absorbed in liquid, then the liquid evaporated. Halite (rock salt) and iron ore are examples of this. Organic rocks come from once-living natural elements like plants. An example of this would be coal and limestone.

METAMORPHIC

Metamorphic rocks are rocks that are transformed from another rock using extreme heat and a lot of pressure. This causes chemical and physical changes.

CLASSIFICATION

Metamorphic rocks are classified by either being foliated or nonfoliated. Foliated rocks can be uneven and have many minerals. Non foliated rocks are rocks that only and made of one mineral. Slate, schist and phyllite are both examples of foliated metamorphic rocks. Marble, antharcite, and quartzite are all nonfoliated.

ROCK CYCLE