Saturday, July 4, 2009

Different Kinds of Rocks

1. Igneous Rocks

1.1 Granite- is a common and widely occurring type of intrusive, felsic, igneous rock.

1.2 Basalt- is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet.

1.3 Gabbro- a dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt.

1.4 Diabase- a mafic, holocrystalline, igneous rock equivalent to volcanic basalt or plutonic gabbro.

1.5 Rhyolite- an igneous, volcanic (extrusive) rock, of felsic (silicon-rich) composition

2. Sedimentary Rocks

2.1 Sandstone- basically sand grains cemented together, which may have been deposited as sand dunes, sand bars, or washed into the sea.

2.2 Coal- It is composed of the remains of plants and animals living millions of years ago.

3. Metamorphic Rocks

3.1 Quartzite- a hard, metamorphic rock which was originally sandstone.

3.2 Marble- a nonfoliated metamorphic rock resulting from the metamorphism of limestone.

3.3 Slate- a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low grade regional metamorphism.

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