metamorphic
Graphite
Graphite (Native Carbon, C)
Hardness: 1-2 (Mohs); Color: Steel gray to black; Luster: Metallic to earthy; Crystal Structure: Hexagonal; Cleavage: Perfect basal; Specific Gravity: 2.09-2.23; Greasy feel and leaves a gray streak on paper.
- Hardness
- 1-2 (Mohs)
- Color
- Steel gray to black
- Luster
- Metallic to earthy
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Physical properties
Hardness: 1-2 (Mohs); Color: Steel gray to black; Luster: Metallic to earthy; Crystal Structure: Hexagonal; Cleavage: Perfect basal; Specific Gravity: 2.09-2.23; Greasy feel and leaves a gray streak on paper.
Formation & geological history
Formed through the regional metamorphism of carbon-rich sedimentary rocks (shales and coals). This particular specimen from Ceylon (Sri Lanka) likely formed in high-grade metamorphic Precambrian terranes through the fluid-deposition of carbon in vein structures.
Uses & applications
Used in lubricants, pencil leads (mixed with clay), electrodes for steelmaking, refractory bricks, brake linings, and high-strength composite materials.
Geological facts
Graphite is one of the softest minerals, yet it shares the exact same chemical composition (carbon) as diamond, which is the hardest natural mineral known. Historically, Sri Lanka (Ceylon) is famous for producing high-purity 'vein' or 'lump' graphite.
Field identification & locations
Identify in the field by its extreme softness (can be scratched by a fingernail), metallic luster, ability to write on paper, and distinctive slippery or greasy feel. Found commonly in marble, schist, and gneiss.
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