metamorphic

Mica-rich metamorphic rock (likely schist)

Muscovite–biotite schist; predominantly phyllosilicate mica minerals in a quartz/feldspar matrix

AI-generated identification · may be incorrect

Visible platy, strongly reflective mica flakes give a sparkly silver-brown appearance and pronounced foliation; individual mica is Mohs 2–3 with perfect basal cleavage, while the whole rock is typically 3–5. The pale gray translucent material along the edge is likely quartz or feldspar; a cavity is also present.

Identified September 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or another clay-rich protolith underwent regional metamorphism, aligning mica under pressure and heat; commonly Paleozoic to Precambrian, depending on locality. Exact age and composition require petrographic or chemical testing.

Uses & applications

Used mainly as decorative stone, landscaping material, and educational or collector specimens; it is generally unsuitable for structural construction because mica-rich foliation can split and weather readily.

Geological facts

The glitter is caused by reflection from thousands of cleavage surfaces, not necessarily metallic mineralization. Brown flakes may be biotite, whereas silvery flakes are commonly muscovite.

Field identification & locations

Identify it by its layered, glittery foliation, flexible or splittable mica sheets, and quartz-rich granular areas; common in regional metamorphic belts worldwide, including New England, the Appalachians, Scandinavia, and the Himalaya.