igneous
Quartz-bearing pegmatite or feldspar-rich rock
Likely granitic pegmatite composed mainly of quartz (SiO₂) and feldspar, with possible mica or iron-oxide staining
AI-generated identification · may be incorrectCoarse, irregular granular texture with translucent gray-white quartz and cream/tan feldspar; vitreous to pearly luster. Quartz hardness is 7 Mohs, feldspar 6–6.5; cleavage may be visible in feldspar, while quartz lacks cleavage.
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Physical properties
Coarse, irregular granular texture with translucent gray-white quartz and cream/tan feldspar; vitreous to pearly luster. Quartz hardness is 7 Mohs, feldspar 6–6.5; cleavage may be visible in feldspar, while quartz lacks cleavage.
Formation & geological history
Formed when silica-rich magma cooled slowly in a vein or pocket, allowing large crystals to grow; commonly Precambrian to Phanerozoic depending on its host terrain. The rusty coloration likely reflects weathering of iron-bearing minerals.
Uses & applications
Used mainly as a collector specimen; similar pegmatite materials provide quartz, feldspar, mica, and occasionally lithium, beryllium, or rare gemstones for industry and jewelry.
Geological facts
Pegmatites are among the best environments for exceptionally large crystals and gem minerals. This small, weathered fragment does not show enough diagnostic crystal form for a precise species identification.
Field identification & locations
Look for interlocking coarse crystals, glassy quartz, blocky feldspar cleavage, and flaky mica; common worldwide, especially in granitic terrains. A hardness test and fresh broken surface would improve identification.
