igneous
Quartz-rich pegmatitic rock (likely granite/pegmatite)
Granite–pegmatite; chiefly quartz (SiO₂), feldspar, and mica, with iron-oxide staining
AI-generated identification · may be incorrectCoarse, interlocking white-gray crystals with reddish-brown hematite/limonite patches and dark mica or amphibole. Quartz hardness 7 and feldspar hardness 6–6.5; generally vitreous to pearly luster, massive texture, and poor overall cleavage because it is an aggregate.
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Physical properties
Coarse, interlocking white-gray crystals with reddish-brown hematite/limonite patches and dark mica or amphibole. Quartz hardness 7 and feldspar hardness 6–6.5; generally vitreous to pearly luster, massive texture, and poor overall cleavage because it is an aggregate.
Formation & geological history
A slowly cooled felsic igneous rock formed from silica-rich magma, commonly in a granite batholith or pegmatite vein. Exact geological age cannot be determined from the photograph; such rocks range from Precambrian to recent in age.
Uses & applications
Used as crushed stone, aggregate, building stone, and landscaping material; attractive pieces may be sold as lapidary or educational specimens, though this example appears primarily collector-grade.
Geological facts
The red-brown coloration is most likely oxidation of iron-bearing minerals rather than a separate red rock. Pegmatitic zones can host large crystals and economically important minerals such as feldspar, mica, tourmaline, and beryl.
Field identification & locations
Identify by its light color, visible coarse crystals, abundant quartz/feldspar, and irregular iron-oxide staining; a fresh break, hand lens, streak, and hardness tests would improve certainty. Common in continental mountain belts and granite terrains worldwide.
