Diamond

Hardness: 10 (Mohs scale), Color: Typically colorless, but impurities can lead to yellow, brown, green, blue, pink, red, black. Luster: Adamantine. Crystal Structure: Isometric (cubic). Cleavage: Perfect octahedral. Specific Gravity: 3.5-3.53.

Formation Process: Diamonds form under extremely high pressure and temperature conditions, typically 150-200 km below the Earth's surface in the mantle. They are brought to the surface through deep-seated volcanic eruptions, primarily in kimberlite and lamproite pipes. Geological Age: Most natural diamonds are between 1 billion and 3.5 billion years old.

Industry: Cutting, drilling, grinding, and polishing tools due to their extreme hardness. Jewelry: Highly prized as gemstones due to their brilliance, fire, and durability. Research: Used in high-pressure experiments due to their strength and transparency. Technology: Used in certain electronic applications.

Diamonds are the hardest known natural material. They are metastable and at surface conditions, graphite is the stable carbon polymorph, but the conversion rate from diamond to graphite is negligible. Large diamonds are often named, such as the Cullinan Diamond, Hope Diamond, and Koh-i-Noor. The oldest known diamonds are 4.25 billion years old.

Identification in the Field: Unlikely to be found as raw, uncut specimens by the average person in the field. When found, they are typically small, irregularly shaped crystals with an adamantine luster. Their extreme hardness can be tested with a scratch test (it will scratch all other minerals). Common Locations: Primary deposits are in kimberlite and lamproite pipes in South Africa, Russia, Botswana, Australia, Canada, and Brazil. Secondary (alluvial) deposits are found in riverbeds and coastal areas where they have been eroded from primary sources. Tips for Collectors: Diamonds for collection are usually purchased cut and polished. Raw diamonds are sought after by specialized collectors, often from known mining regions.