igneous
Coarse-grained igneous rock, likely granitic pegmatite or weathered granite
Granite/pegmatitic granite; chiefly quartz (SiO₂), feldspar, and dark mica or amphibole
AI-generated identification · may be incorrectLight tan-gray, speckled, and granular with pale feldspar/quartz and dark mafic minerals; likely Mohs 6–7, vitreous to dull luster, interlocking crystals, and no obvious cleavage as a whole. The rounded edges suggest natural weathering or abrasion.
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Physical properties
Light tan-gray, speckled, and granular with pale feldspar/quartz and dark mafic minerals; likely Mohs 6–7, vitreous to dull luster, interlocking crystals, and no obvious cleavage as a whole. The rounded edges suggest natural weathering or abrasion.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep underground, typically during Precambrian to Phanerozoic continental crust formation; exact age cannot be determined from the photograph.
Uses & applications
Commonly used as building stone, aggregate, monuments, and countertops; attractive pieces may be collected, but this specimen appears ordinary and has little gem value.
Geological facts
The pale, blocky grains are probably feldspar, translucent gray grains are quartz, and black grains are mica or amphibole. Yellow-brown coloration may be surface staining from iron oxidation or weathering.
Field identification & locations
Identify by its coarse interlocking texture and mixed light/dark minerals; a vinegar test is irrelevant, while a steel scratch test should not easily scratch quartz. Common worldwide in continental mountain belts and exposed batholiths.
