igneous
Weathered granite (likely granitic river cobble)
Granite; predominantly quartz, feldspar, and mica
AI-generated identification · may be incorrectMedium- to coarse-grained, pinkish tan and gray, with a dull to slightly granular luster; Mohs hardness about 6–7, no prominent cleavage as a whole, and high durability. Rounded edges indicate water or glacial abrasion; the image does not resolve individual crystals confidently.
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Physical properties
Medium- to coarse-grained, pinkish tan and gray, with a dull to slightly granular luster; Mohs hardness about 6–7, no prominent cleavage as a whole, and high durability. Rounded edges indicate water or glacial abrasion; the image does not resolve individual crystals confidently.
Formation & geological history
Intrusive felsic magma cooled slowly deep underground, forming interlocking crystals, generally during Precambrian to Phanerozoic continental crust formation; later uplift and weathering produced the rounded cobble.
Uses & applications
Used for building stone, paving, monuments, countertops, aggregate, and landscaping; this specimen has little commercial or collector value.
Geological facts
The pink color commonly comes from potassium feldspar, while darker flecks are biotite or amphibole and translucent grains are quartz. Surface weathering can give granite a rusty tan coating.
Field identification & locations
Identify it by visible interlocking quartz and feldspar grains, high hardness, and lack of layering or fossils; common worldwide, especially in streambeds, glacial deposits, and granite terrains. Estimated value: $1–$10 as a common hand specimen.
