igneous
Pegmatitic granite (quartz–feldspar rock)
Coarse-grained granitic pegmatite, chiefly quartz and feldspar with minor mica
AI-generated identification · may be incorrectCream to tan and gray, coarse interlocking crystals with a glassy-to-pearly luster; quartz is Mohs 7, feldspar about 6, and mica about 2–3. The visible light-colored grains are likely feldspar and quartz; exact minerals cannot be confirmed from the photo alone.
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Physical properties
Cream to tan and gray, coarse interlocking crystals with a glassy-to-pearly luster; quartz is Mohs 7, feldspar about 6, and mica about 2–3. The visible light-colored grains are likely feldspar and quartz; exact minerals cannot be confirmed from the photo alone.
Formation & geological history
Crystallized slowly from silica-rich magma, likely in the late stages of a granitic intrusion; pegmatites commonly form during the final cooling of magma, often billions to millions of years ago depending on the deposit.
Uses & applications
Commonly collected as a specimen; pegmatites can supply feldspar, quartz, mica, and occasionally lithium or rare-element minerals. Attractive varieties are used decoratively, though this piece appears mainly suitable for collecting.
Geological facts
Pegmatites are known for exceptionally large crystals and may contain uncommon minerals, but coarse texture alone does not establish economic rarity.
Field identification & locations
Look for unusually coarse, interlocking quartz and feldspar, with mica flakes sometimes present; common in or near granite bodies worldwide. A hand specimen may show grains but cannot establish its precise locality or mineral identity.
