Graphite

Mohs hardness of 1 to 2; color ranges from steel-gray to black; metallic to earthy luster; hexagonal crystal system; perfect basal cleavage; specific gravity of 2.09 to 2.23.

Forms through the metamorphism of carbon-rich organic materials in sedimentary rocks (regional metamorphism) or as a mineral in igneous and pegmatitic rocks, often billions of years old.

Used in pencils, lubricants, lithium-ion battery anodes, refractories, and in nuclear reactors as a neutron moderator.

Graphite is one of the allotropes of carbon, alongside diamond and fullerenes. Despite both being made entirely of carbon, graphite is extremely soft while diamond is the hardest natural substance on Earth.

Easily identified by its extremely low hardness (leaves a black mark on paper), greasy feel, and metallic gray color. Commonly found in metamorphic rocks worldwide, notably in China, India, Brazil, and Canada.