metamorphic
Mica Schist
Mica Schist (Quartz-Biotite-Muscovite Schist)
Hardness: 3.4-5 on Mohs scale; Color: Silvery-gray, brownish, or golden; Luster: Pearly to metallic (submetallic); Crystal structure: Foliated (schistosity); Cleavage: Perfect basal cleavage in mica grains; Specific gravity: 2.7-3.0.
- Hardness
- 3
- Color
- Silvery-gray, brownish, or golden
- Luster
- Pearly to metallic (submetallic)
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3.4-5 on Mohs scale; Color: Silvery-gray, brownish, or golden; Luster: Pearly to metallic (submetallic); Crystal structure: Foliated (schistosity); Cleavage: Perfect basal cleavage in mica grains; Specific gravity: 2.7-3.0.
Formation & geological history
Formed by the regional metamorphism of shale or mudstone under high pressure and temperature. This process aligns minerals into wavy or platy layers. It can date from various geological eras depending on location, from Precambrian to Cenozoic crustal movements.
Uses & applications
Historically used for building stones and countertops. Today, it is primarily used in construction as a decorative stone, and its mica content is extracted for industrial insulation, paint additives, and cosmetics.
Geological facts
The term schist comes from the Greek word 'schistos,' meaning 'split.' Because of its foliation, it can easily be split into thin slabs. Mica schist is often the source of garnet crystals which are frequently found embedded within the mica layers.
Field identification & locations
Identify in the field by its distinct sparkle (due to mica flakes) and its ability to be split into thin, uneven layers. Look for a dense, wavy 'flow' in the grain. Found commonly in mountainous regions or ancient continental shields like the Appalachian Mountains or the Scottish Highlands.
More like this
