Metamorphic or Sedimentary depending on local grade

Mica-rich Sandstone or Micaceous Schist Weathering

Micaceous Schist (Muscovite-Quartz composition)

Hardness: 2.5-4 (Mohs); Color: Reddish-brown with flashy gold/silver flakes; Luster: Pearly to sub-metallic on flakes, earthy on matrix; Crystal structure: Monoclinic (mica flakes); Cleavage: Perfect basal cleavage in individual mica grains.

Hardness: 2
Color: Reddish-brown with flashy gold/silver flakes
Luster: Pearly to sub-metallic on flakes, earthy on matrix

Identified March 30, 2026More metamorphic or sedimentary depending on local grade →

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Physical properties

Formation & geological history

Formed via the regional metamorphism of clay-rich sedimentary rocks (pelites) or as a lithified micaceous sandstone. The reddish hue indicates secondary oxidation of iron minerals (hematite/limonite coating) due to chemical weathering.

Uses & applications

Common phyllosilicates like mica are used in industrial lubricants, insulation, and cosmetics (shimmer), though these specific weathered fragments are primarily of interest for local geological study or road fill.

Geological facts

The 'flashing' effect is caused by 'books' of muscovite or phlogopite mica that reflect light uniformly. This specific appearance is often mistaken for gold by fledgling prospectors, leading to the nickname 'fool\'s gold' for mica (alongside pyrite).

Field identification & locations

Identify in the field by the 'glitter' effect when rotated in sunlight and the ability to flake off thin, transparent sheets with a needle. Common in Piedmont regions and metamorphic belts.

Other metamorphic or sedimentary depending on local grade specimens

See all

Rough Garnet (Almandine)

Almandine Garnet (Fe3Al2(SiO4)3)

mineral

Gneiss

Gneiss (High-grade metamorphic rock)

metamorphic

Gneiss (specifically Pink Gneiss)

Gneiss (high-grade regional metamorphic rock)

metamorphic

Garnet in Matrix (likely Almandine in Quartz/Mica Schist)

Almandine Garnet (Fe3Al2(SiO4)3) in Quartz-Feldspar host rock

metamorphic

Lapis Lazuli (polished cabochon)

Lazurite-rich metamorphic rock (approx. Na6Ca2Al6Si6O24(SO4,S,Cl)2)

metamorphic

Chert (Jasper variety)

Silicon Dioxide (SiO2)

sedimentary