igneous
Quartz-rich pegmatite (likely)
Quartz–feldspar pegmatite; chiefly SiO₂ quartz with feldspar and possible mica
AI-generated identification · may be incorrectCoarse, irregular pale gray-white and tan crystals with a dull to glassy luster; quartz hardness 7 and feldspar about 6, with no obvious cleavage in quartz. The photograph is insufficient to confirm the minerals or exact rock type.
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Physical properties
Coarse, irregular pale gray-white and tan crystals with a dull to glassy luster; quartz hardness 7 and feldspar about 6, with no obvious cleavage in quartz. The photograph is insufficient to confirm the minerals or exact rock type.
Formation & geological history
Likely crystallized from silica-rich magma in a slowly cooling igneous intrusion, allowing large crystals to grow; pegmatites commonly formed during the late stages of magma crystallization, often billions to millions of years ago.
Uses & applications
Quartz and feldspar are used in glass and ceramics; pegmatites can also host collectible minerals and gemstones. This rough specimen appears to have modest decorative or educational value.
Geological facts
Pegmatites are known for exceptionally large crystals and can contain minerals such as tourmaline, beryl, and mica.
Field identification & locations
Look for interlocking, unusually coarse crystals and distinguish glassy quartz from feldspar’s flatter cleavage surfaces; a closer view or hardness tests would be needed for reliable identification. Pegmatites occur worldwide, especially in granitic regions.
