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Corundum Specimens / Rough (Black)£0.95
Corundum Specimens / Rough (Blue/Sapphire)£2.95
Ruby in Calcite matrix£24.95
Uses and History
Corundum has a couple of obvious uses – the first is, of course, jewellery!
There are two gem quality variants of Corundum – Ruby, which is red, and Sapphire, which occurs in a range of colours. This puts Corundum as two out of the three most commonly used coloured jewellery stones!
Outside of jewellery, there are a few interesting industrial uses – the most common being as an abrasive.
Corundum measures 9 on the Mohs scale, which makes it perfect as an abrasive – perfect for sandpaper and emery. It is sometimes cemented into resins or ceramics to produce abrasive wheels, flap disks, etc.
There are plenty of other industrial uses, including scratch-proof coatings for phone screens, watches, solar panels – it can even be used for spacecraft windows. Corundum can be synthetically created at a relatively low price, due to the simplicity of the Verneuil method – including very large crystals.
Corundum occurs all around the world, with some particularly nice specimen pieces found in Afghanistan, Brazil, China, India, Italy, Kenya, Madagascar, Malawi, Mozambique, Myanmar, Nepal, Norway, Pakistan, Sri Lanka, Switzerland, Tanzania, the USA, and Vietnam.
Ruby is a gem quality variant of Corundum which is a red or pink colour.
Corundum can occur in a wide range of other colours, including colourless, black, blue, red, violet, pink, green, yellow, orange, grey, white and multicoloured pieces.
Photos of Corundum
Photos of Ruby (Red Corundum)
Photos of Sapphire (Various colours of Corundum)
Hazards and Warnings
Unless powdered, there should be no health concerns with Sapphire or Corundum. Aluminium Oxide can be a fire/toxic hazard, but this should not be an issue with the crystalline form.
Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.
When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.
Mandarin and Traditional Chinese: