Rocks and Minerals
By: Trey Hargrave

Sedimentary Rocks

Description: 1) Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3).  2) Sedimentary breccias are a type of clastic sedimentary rock which are made of angular to subangular, randomly oriented clasts of other sedimentary rocks. They are formed by either submarine debris flows, avalanches, mud flow or mass flow in an aqueous medium. 3) Chert (/ˈtʃɜrt/) is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. 4) Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. 5) The energy in coal comes from energy that was stored in giant plants that lived hundreds of millions of years ago in swamp forests, even before the dinosaurs! When these giant plants and ferns died, they formed layers at the bottom of the swamps. Water and dirt began to pile up on top of the dead plant remains.

Ignores Rocks

Description: 1) Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. It has a composition similar to gabbro. 2)Pumice is a type of extrusive volcanic rock, produced when lava with a very high content of water and gases (together these are called volatiles) is extruded (or thrown out of) a volcano. As the gas bubbles escape from the lava, it becomes frothy. 3) Rhyolite a fine-grained igneous rock rich in silica: the volcanic equivalent of granite. rhyolite is what all these little chips are made of scattered on the ground. The rock capping the mesa is an extrusive form of granite called rhyolite. 4) By definition, granite is an igneous rock with at least 20% quartz and up to 65% alkalifeldspar by volume. Granite differs from granodiorite in that at least 35% of thefeldspar in granite is alkali feldspar as opposed to plagioclase; it is the potassiumfeldspar that gives many granites a distinctive pink color. 5) Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth.

Metamorphic Rocks

Description: 1) Schist is made up of  rocks and minerals. Schist is medium grade metamorphic rock, formed by the metamorphosis of mudstone / shale, or some types of igneous rock, to a higher degree than slate, i.e. it has been subjected to higher temperatures and pressures. 2) Gneiss rocks and minerals. Gneiss is a high grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of granite, or sedimentary rock. 3) Marble is a metamorphic rock form composed of coarse crystals from parent-limestone or dolostone rocks. Pure marble is white and composed of the mineral calcite. It has been very popular for sculpture and building construction because of its beauty and relative softness. 4) When sandstone is cemented to quartzite, the individual quartz grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz-crystals. Most or all of the original texture and sedimentary structures of the-sandstone are erased by the metamorphism. 5) Slate is 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. It is the finest grained foliated metamorphic rock.