Diamond

Minerals of Alberta

Transluscent octahedral diamond and brown diamond

Alberta diamonds. A translucent octahedral diamond and a brown diamond, 0.5 mm scale bars.

Pieces of kimberlite from the Buffalo Head Hills region, Alberta

Pieces of kimberlite from the Buffalo Head Hills, Alberta

Boulder of kimberlite from the Buffalo Head Hills, Alberta

Composition

Diamond is made of elemental carbon atoms that are arranged in a tetrahedral shape. Each tetrahedron is bonded to three others, forming a cube.

Age and Formation

Diamonds form 100 km - 150 km down in the Earth’s mantle at temperatures between 900 °C - 1200 °C. Deep volcanic events push molten rock up through the crust where it erupts through the surface. These eruptions form carrot-shaped structures (kimberlite pipes) that are filled with broken crustal rock, igneous rocks (including kimberlite and xenoliths), and sometimes diamonds. In Alberta, about 50 kimberlite pipes ranging in age from 60 - 90 million years old have been discovered nearly all in the Buffalo Head Hills region.

Important properties

Diamond is the hardest and least compressible naturally occurring mineral. It conducts heat 5 times greater than silver which is the most conductive metal. Diamonds range in size and form and can be cut into various shapes. Cut and polished diamonds sparkle brilliantly.

Uses

Most diamonds are not gem quality and are used for abrasives or cutting tools. Gem quality specimens are for jewelry. Clarity, colour, carat (weight), and cut affect the value of diamond gemstones. Specialty lenses, and surgical and dental instruments, may be made from diamonds. Diamonds are not produced commercially in Alberta.