Mineralogy & Petrology
sedimentary rocks
Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth’s surface. Sedimentary rocks often have distinctive layering or bedding. Many of the picturesque views of the desert southwest show mesas and arches made of layered sedimentary rock.
METAMORPHIC ROCKS
Metamorphic rocks form when high temperatures and pressure act on a rock to alter its physical and chemical properties (metamorphism means ‘to change form’). These conditions often stretch, twist and fold the rock as it cools. In metamorphic rocks some or all of the minerals in the original rock are replaced, atom by atom, to form new minerals
igneous rocks
Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface. Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies.
minerals
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.