Graphite

Hardness: 1-2.5 (Mohs scale), Color: Silvery-gray to black, metallic luster; often tarnishes dull. Streak is black. Luster: Metallic to sub-metallic. Crystal Structure: Hexagonal system, typically found in leafy, flaky, or massive forms. Cleavage: Perfect basal cleavage, allowing it to split into thin flexible sheets. Specific Gravity: 2.09-2.23.

Graphite forms under high temperature and pressure conditions in metamorphic rocks (e.g., schists, gneisses, marbles) and igneous rocks. It can also form during the metamorphism of organic-rich sedimentary rocks (e.g., coal seams). Geological Age: Varies widely, depending on the host rock formation, from Precambrian to recent.

Industry: Pencils (mixed with clay), lubricants, electrodes, refractories (linings for high-temperature furnaces), batteries (especially lithium-ion batteries), carbon brushes in electric motors, brake linings, and as a neutron moderator in nuclear reactors. It has minimal use in jewelry due to its softness.

Graphite is one of the softest minerals and is an excellent electrical conductor. It is the only non-metal element that is a good conductor of electricity. It is also an excellent lubricant and is stable over a wide range of temperatures. Artificial graphite can be produced from petroleum coke or pitch.

Field Identification: Distinguished by its soft, flaky nature, greasy feel, metallic to dull luster, and black streak. It often leaves a mark on paper. It's slippery to the touch. Commonly Found: Major deposits are found in China, India, Brazil, North Korea, and Canada. In the USA, it's found in states like New York, Pennsylvania, and Texas. Tips for Collectors: Handle with care due to its softness. Often associated with quartz, mica, and feldspar in metamorphic rocks.