igneous
Orbicular granite (likely weathered granitic rock with feldspar phenocryst)
Granite; chiefly quartz, K-feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; coarse-grained, pink-orange and black, with a prominent pale feldspar crystal and rusty iron-oxide weathering. Typically has a granular texture and no consistent cleavage as a whole, though feldspar shows cleavage; specific gravity about 2.6–2.8.
Identified More igneous →
Explore Orbicular granite (likely weathered granitic rock with feldspar phenocryst) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6–7 Mohs; coarse-grained, pink-orange and black, with a prominent pale feldspar crystal and rusty iron-oxide weathering. Typically has a granular texture and no consistent cleavage as a whole, though feldspar shows cleavage; specific gravity about 2.6–2.8.
Formation & geological history
Formed when silica-rich magma slowly crystallized deep underground, likely hundreds of millions to billions of years ago; surface weathering produced the brown-red coating. The rounded shape may reflect stream or soil abrasion.
Uses & applications
Used as dimension stone, countertops, aggregate, monuments, and landscaping material; attractive orbicular varieties are collected as decorative specimens. This weathered piece has modest commercial value.
Geological facts
The central light feature is probably a large feldspar phenocryst or weathered mineral pocket, not necessarily a fossil. Iron oxidation commonly creates the vivid reddish-brown coloration.
Field identification & locations
Identify by visible interlocking quartz-feldspar grains, pink coloration, dark mica/amphibole, and hardness sufficient to scratch glass. Common in continental intrusive terrains worldwide, including Scandinavia, India, North America, and Australia.
