mineral

Graphite

Graphite (elemental carbon, C)

AI-generated identification · may be incorrect

Typically dark gray to black with a metallic-to-earthy luster, opaque appearance, perfect basal cleavage, and Mohs hardness 1–2; it leaves a gray-black streak and feels greasy. The layered hexagonal crystal structure commonly produces flaky or foliated surfaces.

Identified September 17, 2026More mineral →

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Physical properties

Formation & geological history

Graphite forms mainly by metamorphism of carbon-rich sedimentary rocks, often during Precambrian to younger regional metamorphism; hydrothermal and igneous occurrences also exist. The specimen appears to be a rough, foliated graphite-rich piece, possibly partly shaped or polished.

Uses & applications

Used for pencils, lubricants, refractories, crucibles, batteries, electrodes, and advanced composites; high-purity material is industrially important, while attractive crystalline specimens are collected.

Geological facts

Graphite and diamond are polymorphs: both are carbon, but graphite’s layered structure makes it soft and conductive, whereas diamond is extremely hard. Its excellent electrical and thermal conductivity distinguishes it from many dark rocks.

Field identification & locations

Identify it by its very low hardness, greasy feel, dark streak, cleavage, and electrical conductivity; common sources include China, Madagascar, Brazil, Canada, Sri Lanka, and the United States. Estimated value: about $5–$30 for a common hand specimen, or $50–$200+ for large, crystalline, high-quality pieces.