They are mined from
kimberlite and lamproite volcanic pipes, which can bring diamond crystals,
originating from deep within the Earth where high pressures and temperatures
enable them to form, to the surface. A diamond is a
transparent crystal of tetrahedrally bonded carbon atoms and crystallizes into
the face centered cubic diamond lattice structure.
Diamonds have been
adapted for many uses because of the material's exceptional physical
characteristics. Most notable are its extreme hardness, its high dispersion
index, and extremely high thermal conductivity (900 – 2320 W/m K), with a
melting point of 3820 K (3547 °C / 6420 °F) and a boiling point of 5100 K (4827
°C / 8720 °F). Naturally occurring diamonds have a density ranging from 3.15 to
3.53 g/cm³, with very pure diamond typically extremely close to 3.52 g/cm³.
The conditions for
diamond formation to happen in the lithospheric mantle occur at considerable
depth corresponding to the aforementioned requirements of temperature and
pressure. These depths are estimated to be in between 140–190 kilometers
(90–120 miles) though occasionally diamonds have crystallized at depths of
300-400 km (180-250 miles)
Tidak ada komentar:
Posting Komentar