igneous
Biotite-rich granite or granodiorite
Felsic intrusive igneous rock; quartz–feldspar–biotite aggregate
AI-generated identification · may be incorrectCoarse-grained, dark gray to brown rock with abundant pale feldspar/quartz and black mica; crystals are interlocking, with vitreous quartz, feldspar cleavage, and Mohs hardness roughly 6–7. The image alone cannot confirm the exact mineral proportions or species.
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Physical properties
Coarse-grained, dark gray to brown rock with abundant pale feldspar/quartz and black mica; crystals are interlocking, with vitreous quartz, feldspar cleavage, and Mohs hardness roughly 6–7. The image alone cannot confirm the exact mineral proportions or species.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the continental crust, producing visible crystals; such rocks commonly range from Precambrian to Mesozoic or younger depending on locality.
Uses & applications
Used as crushed stone, aggregate, dimension stone, monuments, and occasionally decorative slabs; generally not a gemstone or high-value collector material.
Geological facts
The dark flakes are probably biotite mica, while the pale grains are feldspar and quartz; weathering commonly produces rusty brown staining and rough granular surfaces.
Field identification & locations
Identify in the field by its interlocking coarse crystals, abundant quartz/feldspar, and mica sparkle; common in continental mountain belts worldwide, including North America, Europe, India, and Australia.
