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Rocks


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South Florida
Gray Limestone Formation
Coquina -Anastasia Formation
Miami Oolitic Limestone
Miami Oolitic Limestone
Miami Limestone
Fresh-water Limestone,
Bermont Formation
Fresh-water limestone
Bermont Formation
Bermont Formation
Ft. Thompson Formation
Tamiami Formation
Arkansas
Boone Formation
Brentwood Formation
Brentwood Formation

Lamphyerite
South Dakota
Granite Pegmatite
Granite Pegmatite
Graphic Granite
Pyrophillitic Schist
Sandstone
Pegmatite
Pebble Conglomerate
Limestone with Stromatolites
Limestone with Belimnites
Michigan, Minnesota, and Wisconsin
Garnet Schist
Anorthicite
Greenstone
Slicken Sides
(serpentine)
Iron Ore
(Specular Hematite)
Banded Iron Formation
Petosky Stone
Antarctic
Ventifacts
Other
Sandstone
Gold Ore
Speleothem

Labradorite
Oolitic Limestone
Scoria

Phylite
Zebra Sandstone
Native Copper
Pegmatite
Amazonite
Septerian Nodule
Septerian Nodule
Geode
Thunder Egg
Meteorite
Tektite

Petrology is the study of rocks, their composition, and the conditions that lead to their creation. Rocks are composed of minerals. There are 3 main types of rock, igneous, metamorphic, and sedimentary.

Igneous rocks are formed as melted material from the earth's interior cools to become rock. This cooling may have occurred within the earth. If this is the case then the crystal size will generally be large enough to see and the rock is called a plutonic rock. If the rock is forced out on to the surface of the earth then it will cool fairly quickly and there will not be time for minerals to form. This type of rock is called volcanic rock. Most igneous rocks fit into these two very general categories, but there are many types of igneous rocks as you will see below.

Sedimentary rocks are formed as layers of debris are deposited or precipitated and cemented to form rock. These rocks may be composed materials like sand, mud, pebbles, shells, or coral that has been cemented together or be created by precipatation of minerals from the sea. The sedimentary rocks that are composed of rock particles such as sand or mud are called clastic rocks. Those that form by precipatation are called nonclastic.

Metamorphic rocks are those that have been changed as a result of heat or pressure. For example a sandstone (a sedimentary rock composed of cemented sand grains) may become recrystallized under increased pressure and temperature  to become a quartzite. There are two major types of metamorphic rock; foliated and nonfoliated. Foliations are layers so if a metamorphic rocks shows layering or banding it is a foliated rock, if not then it is a nonfoliated rock.