Rock and Mineral Types

Feldspar-(Na, Ca or K) Al(Al,Si)3O8 It is a mineral that is very common, yellow-tan colored Feldspar can be found throughout the Chasm (Image Source 3).

Soapstone 3MgO-4SiO2-H2O- A metamorphic rock, composed mainly out of talc that can be found on the Chasm loop trail.(Image Source 4).

Quartz Si02 vein in rock at Purgatory Chasm. Quartz SiO2- The most common mineral found on Earth, it is transparent (sometimes translucent), brittle, and can be a wide range of colors; white, yellow, purple, black, brown, green, etc. The chasm is riddled with veins of Quartz.

Alaskite at Purgatory Chasm. Alaskite is a granitic rock composed of quartz and alkali feldspar, it is red, white or light gray in color.

Pegmatite Vain at Purgatory Chasm. Pegmatite is a large crystalline igneous rock that mainly contains crystals 1 cm across.

Horneblende - The informal name of the dark green to black amphibole that is found in granite and makes the dark stripe in granite gneiss (Image Source 2).

Granite Gneiss at Purgatory Chasm. Granite Gneiss is a metamorphic rock that forms when the igneous rock granite is exposed to great heat and pressure for a long time.

Granite at Purgatory Chasm. Granite is a light colored (felsic) igneous rock that is mainly composed of quartz, feldspar and some mica (along with other minerals). Granite is intrusive.

Muscovite Mica at Purgatory Chasm. Muscovite Mica is a common member of the Mica mineral family. Muscovite Mica has a tendency to break into sheets. It can be found in several colors; usually brown, yellow, green or even a rose-like color.