igneous
Quartz-rich pegmatite
Granitic pegmatite composed mainly of quartz, with probable feldspar and mica
AI-generated identification · may be incorrectCoarse-grained, irregular tan-brown matrix with white to translucent quartz patches; quartz has Mohs hardness 7 and a vitreous luster, while feldspar is typically 6. The image does not show enough detail to confirm mineral proportions or crystal shapes.
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Physical properties
Coarse-grained, irregular tan-brown matrix with white to translucent quartz patches; quartz has Mohs hardness 7 and a vitreous luster, while feldspar is typically 6. The image does not show enough detail to confirm mineral proportions or crystal shapes.
Formation & geological history
Likely crystallized from silica-rich magma in a slowly cooling, volatile-rich intrusion; pegmatites commonly formed during the late stages of granitic magmatism, often in Precambrian to younger crust.
Uses & applications
Pegmatite is quarried for feldspar, quartz, and mica; attractive or unusually mineral-rich pieces are collected as specimens.
Geological facts
Pegmatites can contain exceptionally large crystals and valuable minerals, including tourmaline and beryl.
Field identification & locations
Look for interlocking, unusually coarse crystals and distinguishable quartz (glassy, no cleavage) from feldspar (cleavage planes). Common worldwide near granite intrusions; a precise identification would require closer examination.
