Rocks

 
Granite is a type of igneous rock.  It is mainly composed of quarts and feldspar with small amounts of other minerals such as mica and hornblende.  The lighter colors, such as pink, red, gray, and white, come from the quarts and feldspar.  The dark blackish spots can be hornblende or other minerals such as biotite. 



Limestone is usually formed from the accumulation of shell, coral, algal and fecal debris.  It can also be formed by the precipitation of calcium magnesium carbonates from water.  It is mainly composed of different crystal forms of calcium carbonate.  Many consist of grains of skeletal fragments of marine organisms, clay, silt, or sand.  Many limestones exhibit different because of the different amount of impurities within each of them.





The most common and well known types of feldspar make up the greatest percentage of minerals found in Earth's crust.  Feldspar tends to be white or pink in color.  It breaks with a smooth surface.  Feldspar weathers to form kaolin, which is clay.



Schists are a group of metamorphic rocks that are known for containing more than fifty percent platy and elongated minerals.  Heat and pressure draw out individual mineral grains into flaky scales that are easily visible to the human eye.  The individual mineral grains split off easily into flakes or slabs.  Mica schists are the most common type of schist.