diamond

This article is about the mineral. For the gem, see Diamond (gemstone). For other uses, including the shape ◊, see Diamond (disambiguation).
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Diamond
A clear octahedral stone protrudes from a black rock.
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.
Broad
Minerals Category indigenous
Formula
Unit (repeat) C
Strunz classification 01.CB.10a
Identification
Formula mass 12.01 g mol-1 ⋅
Typically yellow, brown or gray to colorless. Less often blue, green, black, translucent white, pink, purple, orange, purple and red.
Crystal habit Octahedral
Crystal system Isometric-Hexoctahedral (Cubic)
Cleavage 111 (perfect in four directions)
Fracture conchoidal (shell)
Mohs hardness scale 10
Luster adamantine
Colorless Streak
Diaphanous transparent to translucent subtransparent
Density 3.52 ± 0.01
Density from 3.5 to 3.53 g/cm3
Polish adamantine luster
Isotropic optical properties
Refractive index 2.418 (500 nm)
No birefringence
No Pleochroism
Dispersion 0.044
Melting point dependent pressure
References [1] [2]
In mineralogy, diamond (Ancient Greek αδάμας - adámas "unbreakable") is an allotrope of metastable atoms, where the carbon atoms are arranged in a variation in the face centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible under normal conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and the thermal conductivity of bulk material. These properties determine the industrial application of diamond in cutting and polishing tools and scientific applications knives diamond and diamond anvil cells.
Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency, this results in the clear appearance, clear of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green (radiation exposure), purple, pink , orange or red. Diamond also has the relatively high optical dispersion (ability to disperse light of different colors), resulting in its characteristic luster. Excellent optical and mechanical properties, including the unmatched strength and durability, make diamond the most popular gemstone.
Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 120 km) in the mantle of the Earth. Minerals containing carbon is the carbon source, and the growth occurs over periods from 1 to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth surface through deep volcanic eruptions by a magma, which cools into kimberlite and lamproite called igneous rocks. Diamonds can also be produced synthetically in a process of high temperature and high pressure which approximately simulates the conditions in the Earth's mantle. An alternative, and completely different growth technology is chemical vapor deposition (CVD). Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have been developed to distinguish natural and synthetic diamonds and diamond simulants.