mineral

Pyrite (iron pyrite)

Pyrite, FeS₂

AI-generated identification · may be incorrect

Brassy yellow metallic luster with granular to poorly cubic crystal form; Mohs hardness 6–6.5, specific gravity about 5.0, brittle, with no prominent cleavage. The surrounding pale, black-speckled material appears to be granite, likely quartz–feldspar–biotite.

Identified September 20, 2026More mineral →

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Physical properties

Formation & geological history

Pyrite forms hydrothermally or during sedimentary/metamorphic processes; this occurrence is plausibly a sulfide grain or nodule in Variscan granite of the Vogtland/Erzgebirge region, roughly 300–350 million years old. The exact host cannot be confirmed from the photograph.

Uses & applications

Used historically as a sulfur source and occasionally for sulfuric-acid production; attractive crystals are collected, but it is rarely used as a gemstone because it tarnishes and is brittle.

Geological facts

Its metallic gold color gives rise to the name “fool’s gold,” though pyrite is harder and more brittle than native gold and commonly forms cubic crystals.

Field identification & locations

Identify it by its pale brass color, metallic luster, brittleness, and possible cubic faces; a streak test gives a greenish-black to brown-black streak, unlike gold’s yellow streak. Common in sulfide veins and granitic hydrothermal zones, including central Europe.