mineral

Likely raw mica-bearing mineral fragment

Possibly biotite mica or a biotite-rich metamorphic fragment; identification is limited by the dark, blurred image

AI-generated identification · may be incorrect

Dark brown to black, shiny/metallic-vitreous luster with apparent flaky cleavage; biotite has Mohs hardness 2.5–3, perfect basal cleavage, and platy crystals. Crystal structure is monoclinic; specific gravity is about 2.7–3.3.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Biotite crystallizes in igneous rocks such as granite and pegmatite and forms during metamorphism of shale or volcanic rocks. Its age depends on the host rock, ranging from recent to billions of years.

Uses & applications

Commonly collected as a mineral specimen and used scientifically to estimate geological ages; abundant biotite has limited industrial value, though mica broadly is used in insulation, pigments, and fillers.

Geological facts

Thin biotite sheets can be peeled into flexible, translucent flakes and commonly show a dark bronze sheen. The specimen could also be a small sulfide or weathered rock fragment, which would require a sharper image or tests for confirmation.

Field identification & locations

Look for elastic, peelable sheets and one perfect cleavage direction; a streak, hardness test, and close inspection can distinguish it from sulfides or dark glass. Biotite is widespread in granites, gneisses, schists, and pegmatites worldwide.