igneous
Weathered quartz-rich rock, likely granite or pegmatite
Granitic pegmatite; chiefly quartz (SiO₂), feldspar, and mica, with possible iron-oxide staining
AI-generated identification · may be incorrectCoarse, irregular crystals with white-gray quartz/feldspar and brown weathered mica or iron oxides; vitreous to dull luster, poor cleavage overall, and approximate hardness 6–7 for quartz/feldspar. The brown coloration may reflect limonite staining or altered biotite.
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Physical properties
Coarse, irregular crystals with white-gray quartz/feldspar and brown weathered mica or iron oxides; vitreous to dull luster, poor cleavage overall, and approximate hardness 6–7 for quartz/feldspar. The brown coloration may reflect limonite staining or altered biotite.
Formation & geological history
Likely crystallized slowly from silica-rich magma in a deep intrusive body or pegmatite vein, generally Precambrian to Phanerozoic in age depending on locality. Surface weathering oxidized iron-bearing minerals and roughened the specimen.
Uses & applications
Granite is used for construction aggregate, dimension stone, and countertops; pegmatites may host collectible quartz, feldspar, mica, and rare-element minerals. This piece appears mainly suitable as a teaching or cabinet specimen.
Geological facts
Quartz is commonly glassy and gray-white, feldspar is blocky and cleavable, and mica may split into thin sheets; these distinctions help confirm the identification.
Field identification & locations
Common in continental mountain belts and exposed intrusive terrains worldwide. A fresh broken surface, hand lens, and hardness test help distinguish it from quartzite or weathered gneiss; exact identification requires locality and testing.
