metamorphic
Polished granite or gneiss cobble
Banding of quartz, feldspar, mica, and ferromagnesian minerals; likely gneiss, possibly weathered granite
AI-generated identification · may be incorrectCoarse-grained, pink-orange and dark gray, with weak compositional banding and granular texture. Quartz and feldspar are Mohs 6–7; overall hardness is about 6–7, with a dull to faintly glassy luster and no obvious cleavage at specimen scale.
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Physical properties
Coarse-grained, pink-orange and dark gray, with weak compositional banding and granular texture. Quartz and feldspar are Mohs 6–7; overall hardness is about 6–7, with a dull to faintly glassy luster and no obvious cleavage at specimen scale.
Formation & geological history
Likely formed from ancient continental crust: granite crystallized slowly underground, and if gneiss, was later intensely metamorphosed and banded under high heat and pressure. Such rocks commonly range from Precambrian to Paleozoic in age.
Uses & applications
Used as durable aggregate, building stone, landscaping rock, and decorative polished stone; this rounded specimen is primarily a collectible or display piece.
Geological facts
The pink color typically comes from potassium feldspar, gray material from quartz and darker silicate minerals, and the streaks reflect mineral segregation or weathering.
Field identification & locations
Identify it by its interlocking crystals, pink feldspar, gray quartz, dark mica/amphibole, and possible foliation; granite is more massive, whereas gneiss shows clearer bands. Common worldwide, especially in old mountain belts and continental shields.
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