igneous
Likely weathered granite or granitic gneiss
Granite: quartz + feldspar + mica; possibly gneiss if the faint banding is structural
AI-generated identification · may be incorrectMedium- to coarse-grained, gray-green specimen with sparkly mica and pale feldspar; quartz is Mohs 7, feldspar 6, mica 2–3. Typically has a vitreous quartz luster, interlocking crystals, and no prominent cleavage as a whole rock.
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Physical properties
Medium- to coarse-grained, gray-green specimen with sparkly mica and pale feldspar; quartz is Mohs 7, feldspar 6, mica 2–3. Typically has a vitreous quartz luster, interlocking crystals, and no prominent cleavage as a whole rock.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in the continental crust; gneiss forms when granite is metamorphosed under high heat and pressure. Such rocks commonly formed during Precambrian to Paleozoic continental events, though the exact age cannot be determined visually.
Uses & applications
Used as dimension stone, countertops, monuments, aggregate, and building material; attractive pieces are collected but generally have little gem value.
Geological facts
The visible glitter likely comes from biotite or muscovite mica, while the pale grains are feldspar and the translucent grains may be quartz.
Field identification & locations
Identify it by its coarse interlocking grains and mixed quartz–feldspar–mica texture; faint alignment or banding would favor gneiss. Common worldwide in continental mountain belts and exposed shields.
