igneous
Weathered, iron-stained feldspathic rock (probable granite or granitic pegmatite)
Quartz–feldspar granitoid; visible blue grains may be altered feldspar or accessory minerals
AI-generated identification · may be incorrectHardness approximately 6–7 Mohs; pale gray-white matrix with rusty brown iron-oxide staining and scattered blue-gray grains. Likely granular, massive, nonfoliated, with little obvious cleavage; exact mineralogy requires testing.
Identified More igneous →
Explore Weathered, iron-stained feldspathic rock (probable granite or granitic pegmatite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness approximately 6–7 Mohs; pale gray-white matrix with rusty brown iron-oxide staining and scattered blue-gray grains. Likely granular, massive, nonfoliated, with little obvious cleavage; exact mineralogy requires testing.
Formation & geological history
Probably a coarse-grained intrusive igneous rock formed by slow cooling of silica-rich magma deep underground, commonly during Precambrian to younger continental crust formation; surface weathering produced the brown staining.
Uses & applications
Used as crushed stone, aggregate, building stone, and occasionally decorative material. This ordinary fragment has little gemstone or collector value.
Geological facts
The blue coloration is not diagnostic and could reflect altered feldspar, sodalite-like material, paint, or surface staining; a thin section or chemical test would be needed for confident identification.
Field identification & locations
Look for interlocking quartz and feldspar grains, a scratch resistance near glass, and no bubbling in dilute hydrochloric acid. Common in continental shields, granite terrains, road cuts, and glacial deposits.
