igneous
Weathered feldspar-rich pegmatite or granite outcrop
Quartz–feldspar granitoid, likely containing potassium feldspar (KAlSi₃O₈) and quartz (SiO₂)
AI-generated identification · may be incorrectCoarse, irregular crystals with tan to salmon-colored feldspar and gray-white quartz in a dark, weathered matrix; feldspar hardness ~6 Mohs, quartz 7, both with vitreous to dull weathered luster. The photograph does not show enough detail to determine the exact rock or mineral proportions.
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Physical properties
Coarse, irregular crystals with tan to salmon-colored feldspar and gray-white quartz in a dark, weathered matrix; feldspar hardness ~6 Mohs, quartz 7, both with vitreous to dull weathered luster. The photograph does not show enough detail to determine the exact rock or mineral proportions.
Formation & geological history
Likely formed when silica-rich magma cooled slowly underground, allowing large crystals to grow; the rock may be Precambrian or younger, but age cannot be identified from the image.
Uses & applications
Granite and pegmatite are used as dimension stone, aggregate, and sources of feldspar and quartz; this appears to be an in-place outcrop rather than a cut specimen.
Geological facts
The prominent tan mass may be a large feldspar crystal or a weathered patch; iron staining commonly gives feldspar-rich rocks warm brown or orange tones.
Field identification & locations
Look for interlocking visible crystals and distinguish feldspar by its blocky cleavage from quartz’s irregular fracture. Similar granitoids occur widely in continental crust; exact identification requires a fresh surface and closer inspection.
