mineral
Diamond (Martapura/Borneo Diamond)
Carbon (C) - Diamond
Hardness: 10 (Mohs scale), Color: Colorless to faint yellow/grey (in image), Luster: Adamantine, Crystal structure: Isometric-hexoctahedral, Cleavage: Octahedral (perfect in four directions), Specific Gravity: 3.51
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Physical properties
Hardness: 10 (Mohs scale), Color: Colorless to faint yellow/grey (in image), Luster: Adamantine, Crystal structure: Isometric-hexoctahedral, Cleavage: Octahedral (perfect in four directions), Specific Gravity: 3.51
Formation & geological history
Formed at high pressure and temperature in the Earth's mantle (140-190 km deep) and brought to the surface via kimberlite or lamproite pipes. Commonly found in secondary alluvial deposits (river beds) in Kalimantan.
Uses & applications
Used primarily in jewelry as a gemstone and in industrial applications for cutting, grinding, and drilling due to extreme hardness.
Geological facts
The coordinates provided (3.3°S, 114.6°E) are near Martapura, Indonesia, famously known as the 'City of Diamonds.' The Cempaka diamond mine nearby is a well-known source for these specimens.
Field identification & locations
Identify by extreme hardness (scratches all other minerals) and high refractive index. In South Kalimantan, they are often found in alluvial gravels through traditional panning.
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