Diamond

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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.
General
Category Native Minerals
Formula
(repeating unit)
C
Strunz classification 01.CB.10a
Identification
Formula mass 12.01 g⋅mol−1
Color Typically yellow, brown or gray to colorless. Less often blue, green, black, translucent white, pink, violet, orange, purple and red.
Crystal habit Octahedral
Crystal system Isometric-Hexoctahedral (Cubic)
Twinning Spinel law common (yielding "macle")
Cleavage 111 (perfect in four directions)
Fracture Conchoidal (shell-like)
Mohs scale hardness 10 (defining mineral)
Luster Adamantine
Streak Colorless
Diaphaneity Transparent to subtransparent to translucent
Specific gravity 3.52±0.01
Density 3.5–3.53 g/cm3
Polish luster Adamantine
Optical properties Isotropic
Refractive index 2.418 (at 500 nm)
Birefringence None
Pleochroism None
Dispersion 0.044
Melting point Pressure dependent
References [1][2]

A diamond (from the ancient Greek αδάμας – adámas "unbreakable") is a re-arrangement of carbon atoms (those are called allotropes).

Diamonds have the highest hardness of any bulk (all one type) material. Because of this, many important industries use diamonds as tools for cutting and polishing things. Many of them are clear, but some of them have colors, like yellow, red, blue, green and pink. Diamonds of a different color are called "fancies".

Big diamonds are very rare, and are worth a lot of money. Only 20% of diamonds are fit for jewelry. The other 80% are not pretty enough. They are industrial diamonds, used to make things like drill bits and diamond saws. This is because even a diamond that is not beautiful is useful because It is very hard..

Because many diamonds are beautiful, people make jewellery using them. Diamonds are very effective electrical insulators, but also very good conductors of heat. On Mohs scale of mineral hardness, diamonds are scored as 10 (the highest score possible).

Formation of diamonds[change | change source]

There are natural and synthetic diamonds. The Earth makes natural diamonds, and people make synthetic diamonds. Diamonds are the hardest natural substance known to man. Diamonds are made of pure carbon, the same chemical element as graphite, fullerene, and coal. But diamonds are very hard and in crystalline form. It is commonly believed that diamonds are formed from coal, but this is not true.

Diamonds are made deep in the Earth where there is an intense amount of pressure and heat. The formation of natural diamonds needs specific conditions. These are exposure of carbon-bearing materials to high pressure, between 45 and 60 kilobars (4.5 and 6 GPa), but at a comparatively low temperature, between about 900 and 1,300 °C (1,650 and 2,370 °F). These conditions are found in two places on Earth: in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike.[3]

People find diamonds where volcanoes were a long time ago, or at the site of a meteorite strike. Sometimes people find diamonds on the top of the ground. But in places like South Africa, they must dig deep down into a diamond mine to get diamonds. Diamonds were first found in India.

Trading in diamonds[change | change source]

For many decades the trading of diamonds has been controlled by the De Beers group of companies. It is fairly well known that diamonds are not rare, but are stockpiled so that the price never goes down. It is not quite a monopoly, because some mines are not owned by De Beers, but the group has companies all over the world which work together to manipulate the market.[4]

References[change | change source]

  1. "Diamond". Mindat. http://www.mindat.org/min-1282.html. Retrieved July 7, 2009.
  2. "Diamond". WebMineral. http://webmineral.com/data/Diamond.shtml. Retrieved July 7, 2009.
  3. Carlson R.W. 2005. The mantle and core. Elsevier. p. 248. ISBN 0-08-044848-8. https://books.google.com/?id=1clZ4ABsfoAC&pg=PA248.
  4. Epstein, Edward Jay 1982. The diamond invention (Complete book, includes Chapter 20: Have you ever tried to sell a diamond?)

Other websites[change | change source]