metamorphic

Pyrite-bearing schist (likely mica schist)

Muscovite/biotite schist with disseminated pyrite (FeS₂)

AI-generated identification · may be incorrect

Fine- to medium-grained, strongly glittery surface from platy mica, with brassy metallic pyrite flecks. Mica hardness is about 2–3 Mohs; pyrite is 6–6.5, with perfect mica cleavage and a generally foliated texture.

Identified September 17, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or mudstone underwent regional metamorphism, recrystallizing clay minerals into mica; pyrite formed from iron- and sulfur-rich fluids or original sulfides. Typically Paleozoic to Precambrian, depending on locality.

Uses & applications

Used mainly as a decorative or collectible specimen; mica schist can be used locally as fill or dimension stone, while pyrite has limited industrial sulfur and mineral-collector value.

Geological facts

The golden sparkle may be mistaken for gold, but pyrite is harder, brittle, and commonly forms angular grains. A streak test gives pyrite a greenish-black to brownish-black streak, unlike gold’s yellow streak.

Field identification & locations

Common in metamorphic belts worldwide, including New England, the Appalachians, Scotland, and parts of Scandinavia. Identify by foliation, flaky mica sparkle, and hard brassy grains; avoid relying on color alone.