igneous
Red-brown granite or granitic pegmatite fragment
Granite; chiefly quartz (SiO₂), feldspar, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, reddish-brown and black, with a vitreous-to-pearly luster; typical hardness is about 6–7 Mohs, no dominant cleavage as a rock, and specific gravity about 2.6–2.8. The image suggests interlocking translucent quartz and pink/orange feldspar with dark mica or amphibole.
Identified More igneous →
Explore Red-brown granite or granitic pegmatite fragment in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse-grained, reddish-brown and black, with a vitreous-to-pearly luster; typical hardness is about 6–7 Mohs, no dominant cleavage as a rock, and specific gravity about 2.6–2.8. The image suggests interlocking translucent quartz and pink/orange feldspar with dark mica or amphibole.
Formation & geological history
Slow cooling of silica-rich magma deep in Earth’s crust produced the visible crystals, generally during Precambrian to Phanerozoic mountain-building events. Exact age and locality cannot be determined from the photograph.
Uses & applications
Widely used as dimension stone, countertops, monuments, aggregate, and decorative landscaping material; attractive pieces may be collected but are generally low-value.
Geological facts
The reddish color commonly comes from iron-oxidized potassium feldspar, while dark flakes may be biotite mica or hornblende.
Field identification & locations
Identify it by its coarse interlocking crystals, pink feldspar, glassy quartz, and black minerals; a streak test is usually white, and it will not fizz with dilute hydrochloric acid. Common worldwide in continental crust and quarry regions.
