metamorphic
Biotite Schist
Metamorphic Rock (Schist)
Hardness varies from 3 to 4 on the Mohs scale for the mica flakes, color is typically grayish-brown to dark brown or black with a prominent silvery or golden sparkle, luster is pearly to metallic on cleavage planes, crystal structure is foliated with platy minerals aligned in parallel bands (schistosity).
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Physical properties
Hardness varies from 3 to 4 on the Mohs scale for the mica flakes, color is typically grayish-brown to dark brown or black with a prominent silvery or golden sparkle, luster is pearly to metallic on cleavage planes, crystal structure is foliated with platy minerals aligned in parallel bands (schistosity).
Formation & geological history
Formed through regional metamorphism of pelitic sedimentary rocks such as shales and mudstones, or sometimes igneous rocks, subjected to high temperatures and pressures over millions of years, typically occurring during mountain-building events.
Uses & applications
Primarily used in academic study, geological education, and as a low-grade decorative stone or local aggregate where available.
Geological facts
Schist is characterized by its strong foliation, which allows it to split into thin flakes or slabs. The sparkling appearance in this specimen is due to abundant biotite and muscovite mica flakes reflecting light.
Field identification & locations
Easily identified in the field by its distinct foliation and visible, sparkling mica flakes. Commonly found in orogenic belts and regions with ancient continental shields.
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