US Geological survey, Mineral Commodities summaries, Feb 2019.
------------
National Minerals Information Center Graphite Statistics and Information
Graphite is a soft, crystalline form of carbon. Other forms are diamond and fullerenes ("buckyballs").It is gray to black, opaque, and has a metallic luster. It is flexible but not elastic.Graphite occurs naturally in metamorphic rocks such as marble, schist, and gneiss. It exhibits the properties of a metal and a nonmetal, which make it suitable for many industrial applications. The metallic properties include thermal and electrical conductivity. The nonmetallic properties include inertness, high thermal resistance, and lubricity. Some of the major end uses of graphite are in high-temperature lubricants, brushes for electrical motors, friction materials, and battery and fuel cells.
