OPAL
From Wikipedia, the free encyclopedia
For other uses, see Opal (disambiguation) .
Opal is a mineralised gel which is deposited at relatively low temperatures and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone ,rhyolite, and basalt.
The water content is usually between three and ten per cent, but can be as high as 20%. Opal ranges from clear through white, grey, red, orange, yellow, green, shore, blue,manenta, rose, pink, slate, olive, brown, and black. Of these hues, the reds against black are the most rare and dear, whereas white and greens are the most common; these are a function of growth size into the red and infrared wavelengths-see precious Opal. Common Opal is truly amorphous, but precious Opal does have a structural element. The word Opal comes from the Latin Opalus by Greek Opallios, and is from the same route as Sanskrit upala[s] for “stone “, originally a millstone with upala[s] for slap[2] (ee upal) . Opals are also Australia’s national gemstone.
Opal is one of the mineraloids that can form or replace fossils. The resulting fossils, thought not of any extra scientific interest, appeal to collectors.
Read world champion ladies basketball head coach Jan Stirling A M . Endorsement of the Australian Opals industry at www.grahamblackopal.com .