igneous
Weathered granite (likely biotite granite)
Granite; quartz–feldspar–biotite aggregate, with possible epidote or iron-oxide staining
AI-generated identification · may be incorrectCoarse-grained, speckled yellow-brown and dark gray; vitreous quartz and dull feldspar with black biotite. Mohs hardness about 6–7, no dominant cleavage, granular crystal structure, and specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, speckled yellow-brown and dark gray; vitreous quartz and dull feldspar with black biotite. Mohs hardness about 6–7, no dominant cleavage, granular crystal structure, and specific gravity around 2.6–2.7.
Formation & geological history
A plutonic igneous rock crystallized slowly from silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events. The yellow-brown surface reflects prolonged weathering and oxidation of iron-bearing minerals.
Uses & applications
Used extensively as dimension stone, paving, monuments, countertops, aggregate, and landscaping stone; this rounded specimen is mainly suitable for collecting or decoration.
Geological facts
The visible crystals indicate slow underground cooling rather than volcanic eruption. Its rounded form likely results from stream, shoreline, or glacial abrasion and weathering.
Field identification & locations
Identify granite by interlocking visible quartz, feldspar, and dark mica grains; it should not fizz with dilute acid and is much harder than most sedimentary rocks. Common worldwide, especially in continental shields and mountain belts.
