The finest opal known is obtained in the Upper Cretaceous formation at White Cliffs, near Wilcannia, New South Wales, and at these mines about 700 men find constant employment.
Other precious stones, including the sapphire, emerald, oriental emerald, ruby, opal, amethyst, garnet, chrysolite, topaz, cairngorm, onyx, zircon, etc., have been found in the gold and tin bearing drifts and river gravels in numerous localities throughout the states.
The opal was mined here Boo years ago, and the largest piece hitherto found, weighing 2940 carats and estimated to have a value of £175,000, is preserved in the Court Museum at Vienna.
For other forms of silica see OPAL and TRIDYMITE.
Hungary is the only country in Europe where the opal is found, namely at the famous mines of Vorosvagas in the county of Sáros, and at NagyMihaly in that of Zemplin.
The dull green was followed successively by amber, white opal, blue opal, straw opal, sea-green, horn colour and various pale tints of soda-lime glass, ranging from yellow to blue.
Experiments were also tried with a violet-coloured glass, a violet opal, a transparent black and with glasses shading from red to blue, red to amber and blue to green.
It is found in the form of oxide (silica), either anhydrous or hydrated as quartz, flint, sand, chalcedony, tridymite, opal, &c., but occurs chiefly in the form of silicates of aluminium, magnesium, iron, and the alkali and alkaline earth metals, forming the chief constituent of various clays, soils and rocks.
Many semi-precious and precious stones are found in Utah, including garnet (long sold to tourists by the Navaho Indians), amethyst, jasper, topaz, tourmaline, opal, variscite (or " Utahlite "), malachite, diopside and Smithsonite.
She was surprised to recognize the Council members, from tall, thin Opal to the Council members whose names she'd never learned.
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The chief economic product of the Desert Sandstone is opal, which occurs in it at White Cliffs and Wilcannia.
A'Ran responded by tipping his chin, and Jetr's attention returned to Opal, who had been speaking too long already.
"We will meet after we dine this evening," Opal said.
Opal, the head of the Council, rose gracefully, pulling A'Ran from his thoughts.
Opal, the tall, thin man, nodded and stepped toward the house.
The opal beds contain Cretaceous fossils such as Cimoliosaurus.
If the bead is coloured we may have present: cobalt, blue to violet; copper, green, blue on cooling; in the reducing flame, red when cold; chromium, green, unaltered in the reducing flame; iron, brownish-red, light-yellow or colourless on cooling; in the reducing flame, red while hot, yellow on cooling, greenish when cold; nickel, reddish to brownish-red, yellow to reddish-yellow or colourless on cooling, unaltered in the reducing flame; bismuth, yellowish-brown, light-yellow or colourless on cooling; in the reducing flame, almost colourless, blackish-grey when cold; silver, light yellowish to opal, somewhat opaque when cold; whitish-grey in the reducing flame; manganese, amethyst red, colourless in the reducing flame.
The mineral is also used in the production of opal glass and enamel ware.
Opal, meet me in the command center, A'Ran directed.