metamorphic

Quartz–mica schist or mica-rich quartzite

Quartz with muscovite/biotite mica; likely a quartz-mica schist, possibly pegmatitic

AI-generated identification · may be incorrect

Hardness is approximately 2–7: quartz is Mohs 7, while mica flakes are 2–3. It has translucent gray-to-tan quartz, reflective platy mica, dark biotite-rich patches, and a vitreous to pearly luster; foliation is visible where mica layers occur, though the specimen appears strongly veined and brecciated.

Identified September 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sedimentary or igneous rock underwent regional metamorphism, recrystallizing quartz and aligning mica; some portions may represent quartz veins or pegmatitic material. The exact geological age cannot be determined from the photograph.

Uses & applications

Primarily a collecting and teaching specimen; comparable quartzite is used as crushed stone and building or decorative material, while mica has industrial electrical and insulation applications. It is generally not suitable for jewelry unless attractive quartz or mica crystals are present.

Geological facts

The contrasting dark patches are likely biotite or other mafic minerals, while the silvery reflective flakes are mica. A fresh broken surface and hand lens would distinguish schist from massive quartzite more reliably.

Field identification & locations

Common in metamorphic terrains worldwide, including mountain belts and regions with quartz veins. Look for foliated, sparkly mica layers, glassy quartz, and a lack of uniform granular texture; acid testing is unnecessary.