Diamond

Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At room temperature and pressure, another solid form of carbon known as graphite is the chemically stable form of carbon, but diamond converts to it extremely slowly. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools. They are also the reason that diamond anvil cells can subject materials to pressures found deep in the Earth.Diamond

The slightly misshapen octahedral shape of this rough diamond crystal in matrix is typical of the mineral. Its lustrous faces also indicate that this crystal is from a primary deposit.GeneralCategoryNative mineralsFormula
(repeating unit)CIMA symbolDia^[1]Strunz classification1.CB.10aDana classification1.3.6.1Crystal systemCubicCrystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)Space groupFd3m (No. 227)StructureJmol (3D)Interactive imageIdentificationFormula mass12.01 g/molColorTypically yellow, brown, or gray to colorless. Less often blue, green, black, translucent white, pink, violet, orange, purple, and red.Crystal habitOctahedralTwinningSpinel law common (yielding “macle”)Cleavage111 (perfect in four directions)FractureIrregular/UnevenMohs scale hardness10 (defining mineral)LusterAdamantineStreakColorlessDiaphaneityTransparent to subtransparent to translucentSpecific gravity3.52±0.01Density3.5–3.53 g/cm³ 3500–3530 kg/m³Polish lusterAdamantineOptical propertiesIsotropicRefractive index2.418 (at 500 nm)BirefringenceNonePleochroismNoneDispersion0.044Melting pointPressure dependent