igneous
Weathered iron-stained granite or granitic gneiss
Quartz–feldspar–mica granitoid, likely altered and weathered
AI-generated identification · may be incorrectCoarse, irregular texture with tan-brown iron-oxide staining, pale feldspar/quartz, and dark mica or mafic inclusions; typical hardness is about 6–7 Mohs, with vitreous quartz and dull earthy weathered surfaces. No clear crystal faces or cleavage are visible because the specimen is strongly rounded and altered.
Identified More igneous →
Explore Weathered iron-stained granite or granitic gneiss in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse, irregular texture with tan-brown iron-oxide staining, pale feldspar/quartz, and dark mica or mafic inclusions; typical hardness is about 6–7 Mohs, with vitreous quartz and dull earthy weathered surfaces. No clear crystal faces or cleavage are visible because the specimen is strongly rounded and altered.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the crust, then was uplifted, fractured, chemically weathered, and rounded by transport; commonly Precambrian to Mesozoic in age depending on locality.
Uses & applications
Granite is widely used as dimension stone, countertops, paving, monuments, and aggregate; an unusual small piece has modest educational or lapidary value.
Geological facts
The orange-brown coloration generally results from oxidation of iron-bearing minerals or staining by groundwater. The dark cavities may be weathered mafic minerals or small vugs.
Field identification & locations
Identify it by its granular interlocking texture, abundant pale quartz/feldspar, hardness, and lack of layering; a steel nail should not scratch fresh surfaces, while glass may be scratched by quartz. Common worldwide in granitic terrains and stream gravels.
