Pyrite

Hardness of 6-6.5 on the Mohs scale, brassy yellow color with a metallic luster, cubic crystal system, and a greenish-black streak.

Forms in a wide variety of geological environments from hydrothermal veins to sedimentary rocks, often precipitated from reducing aqueous solutions.

Used historically for ignition in firearms, currently utilized in the manufacture of sulfur dioxide and sulfuric acid, and widely collected as a mineral specimen.

Commonly known as 'Fool's Gold' due to its superficial resemblance to actual gold, though it is harder and more brittle.

Identified by its brassy metallic color, high specific gravity, and cubic or pyritohedral crystal habits; found globally with major deposits in Peru, Spain, and the United States.