igneous

Quartz-rich pegmatite (milky quartz with feldspar)

Quartz (SiO₂)–feldspar pegmatite, likely containing albite or orthoclase

AI-generated identification · may be incorrect

Hardness about 6–7 (quartz) and 6–6.5 (feldspar); white to cream, translucent grains with vitreous to pearly luster. Coarse interlocking crystals, uneven fracture, and feldspar cleavage are visible; iron staining causes the tan coloration.

Identified September 12, 2026More igneous →

Explore Quartz-rich pegmatite (milky quartz with feldspar) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Quartz-rich pegmatite (milky quartz with feldspar)
Scientific name: Quartz (SiO₂)–feldspar pegmatite, likely containing albite or orthoclase
Category: igneous
Identified: September 12, 2026
Method: Standard

AI Estimated Value

Approximately $5–$30 for a common hand specimen; $50–$200+ if unusually large, crystal-rich, or containing collectible accessory minerals.

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 from the final, water-rich melt of a granite intrusion, allowing exceptionally large crystals to grow, typically during the Precambrian to Phanerozoic. Common in granitic pegmatite veins and dikes.

Uses & applications

Used as a source of quartz and feldspar for glass, ceramics, aggregates, and ornamental stone; attractive pieces are collected but generally have modest value.

Geological facts

Pegmatites can host rare minerals and gemstones such as tourmaline, beryl, lithium minerals, and topaz. The specimen’s rusty coating likely reflects oxidation of iron-bearing minerals or surface weathering.

Field identification & locations

Identify it by its very coarse texture, glassy quartz, and blocky, cleavable feldspar; it is not likely a single mineral crystal. Common worldwide in regions with granite, including Brazil, Madagascar, the United States, and Scandinavia.