igneous
Weathered granite or granitic gneiss
Granite; chiefly quartz, feldspar, and mica, possibly with gneissic foliation
AI-generated identification · may be incorrectCoarse-grained, gray to dark gray rock with pale feldspar/quartz and dark mica or amphibole; minerals show glassy to dull luster, no consistent cleavage as a whole, and Mohs hardness about 6–7. The layered or streaked appearance suggests partial metamorphic alteration.
Identified More igneous →
Explore Weathered granite or granitic gneiss in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse-grained, gray to dark gray rock with pale feldspar/quartz and dark mica or amphibole; minerals show glassy to dull luster, no consistent cleavage as a whole, and Mohs hardness about 6–7. The layered or streaked appearance suggests partial metamorphic alteration.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep underground, typically during Precambrian to younger continental mountain-building events; gneissic textures form when granite is subjected to intense heat and pressure. The rough outer surface reflects weathering and erosion.
Uses & applications
Commonly used as crushed aggregate, road stone, building stone, countertops, monuments, and landscaping material; this small specimen has mainly educational or collecting value.
Geological facts
Quartz is usually translucent-gray and glassy, feldspar is white or pink, and mica/amphibole produces dark flakes or bands. Granite and gneiss are among the most widespread continental rocks.
Field identification & locations
Identify it by visible interlocking light and dark mineral grains, strong hardness, and lack of fizz with dilute acid; a streaked mineral alignment favors gneiss over granite. Common worldwide in continental shields and mountain belts.
