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Opals
Opal is a non-crystalline solid which is not really a mineral but is actually a mineraloid. It is often used as an accessory for jewelry because of its translucent characteristics. About 97% of the world’s opals are produced in Australia.
334 Questions
When they have just been mined they come in all sorts of shapes and sizes but once they have been polished and cut, they are usually round and smooth.
Opals can actually be made from metals and non-metals and are of perticluar interest in modern nanotechnology because they posess something called a photonic bad gap. This basically allows no light of a certain wavelength to propagate through the structure. Natural opals are formed from silicon dioxide otherwise known as silica. In research opals are commonly created from silica, silicon, PMMA and polystyrene.
The fracture of an opal can be hard or smooth , An opal can have as many fractures as any other mineral can . Sometimes opal can be smooth , sometimes they can be hard . The fracture of an opal is hard and smooth .
Where does about 95 percent of the worlds opal the mineral come from?
95% of the opla supply comes from Australia.
In which country is the town of Coober Pedy?
Coober Pedy is a town in northern South Australia, 846 km north of Adelaide. So: the correct answer is that Coober Pedy is in the country of Australia, specifically the state of South Australia.
I like the pun...if that was your intention. Opal rough (rock before it's cut) tends to be on the softer side than the other precious gemstones (ruby, sapphire, emerald). It has a hardness between 5.5-6.5 on the mohs scale. So opals when constantly worn could become scratched and needs to be repolished time to time
