igneous

Quartz-rich pegmatite with muscovite mica

Granitic pegmatite; primarily quartz (SiO₂), with muscovite mica [KAl₂(AlSi₃O₁₀)(OH)₂] and possibly feldspar

AI-generated identification · may be incorrect

Hardness is about 2–2.5 for muscovite and 7 for quartz; the specimen is white to translucent with glassy quartz and pearly, platy mica. Quartz has no cleavage, while muscovite has perfect basal cleavage; crystals are typically coarse-grained and interlocking.

Identified September 16, 2026More igneous →

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At a glance

Common name: Quartz-rich pegmatite with muscovite mica
Scientific name: Granitic pegmatite; primarily quartz (SiO₂), with muscovite mica [KAl₂(AlSi₃O₁₀)(OH)₂] and possibly feldspar
Category: igneous
Identified: September 16, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common rough specimen; $50–$200 or more for unusually large, clean crystals.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Formed when volatile-rich granitic magma cooled slowly in a late-stage dike or vein, allowing exceptionally large crystals to grow. Pegmatites are generally Precambrian to Phanerozoic, depending on the host intrusion.

Uses & applications

Used as a collector specimen; quartz and feldspar pegmatites may provide industrial minerals, while mica is used in electrical insulation, fillers, and cosmetics. This rough piece has little jewelry or construction value.

Geological facts

The large mica flakes and sugary, translucent quartz are characteristic of pegmatitic texture. Minor yellow-brown staining likely represents iron oxides from weathering.

Field identification & locations

Identify it by very coarse crystals, translucent glassy quartz, and mica sheets that split into flexible flakes. Common in granite terrains worldwide, including Brazil, the United States, Madagascar, and Norway.