Diamond

Hardness: 10 (Mohs scale), Color: Typically colorless, but impurities can result in yellow, brown, green, blue, pink, red, black. Luster: Adamantine. Crystal Structure: Isometric (cubic), commonly octahedral or dodecahedral. Cleavage: Perfect octahedral (four directions). Specific Gravity: 3.5–3.53.

Formed under immense pressure and high temperatures (900-13000C) at depths of 140-190 kilometers (90-120 miles) within the Earth's mantle. Their geological age is typically billions of years old, often predating the formation of the continents where they are found.

Jewelry (gemstones), industrial abrasives (cutting, grinding, drilling), high-tech applications (heat sinks, optical windows, quantum computing).

Diamonds are the hardest known natural material. They form deep within the Earth's mantle and are brought to the surface through volcanic eruptions in kimberlite and lamproite pipes. Only about 20% of mined diamonds are gem-quality, with the rest used for industrial purposes.

Diamonds are identified by their extreme hardness (will scratch any other mineral), adamantine luster, and often characteristic octahedral crystal habit (though many are found as fragments). They are commonly found in kimberlite pipes (primary deposits) and alluvial deposits (secondary deposits after erosion from kimberlite). Major diamond producing countries include Russia, Botswana, Canada, Australia, and South Africa. Field identification often involves hardness tests and observation of luster and crystal form, though definitive identification requires laboratory analysis.