The Halley's Comet Opal is the largest uncut black
opal
Opal is a hydrated amorphous form of silicon dioxide, silica (SiO2·''n''H2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a ...
in the world, according to the ''
Guinness Book of World Records
''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a British reference book published annually, listi ...
''. It is so named because it was unearthed in 1986, a year when
Halley's Comet
Halley's Comet is the only known List of periodic comets, short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparitions (25 of 30) occurring after ...
could be seen from Earth. It is the third largest gem grade black opal ever recorded, the largest one extant, and the largest specimen ever found in its region. It was found at
Lightning Ridge, New South Wales
Lightning Ridge is a small outback town in north-western New South Wales, Australia. Part of Walgett Shire, Lightning Ridge is situated near the southern border of Queensland, about east of the Castlereagh Highway. The Lightning Ridge area ...
,
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, by the Lunatic Hill Mining Syndicate. It weighs and is about the size of a man's fist. The Halley's Comet Opal is a very fine specimen, with few flaws or blemishes and a large green and orange thick color bar which goes through the opal. Formed about 20 million years ago, it is an example of a nobby, which is a natural lump-shaped opal found only at Lightning Ridge. As of 2006 it was for sale at
$1.2 million.
See also
*
List of individual gemstones
A number of individual gemstones are famous in their own right, either because of their size and beauty or because of the people who owned or wore them.
Aquamarines
* Dom Pedro, the world's largest cut and polished aquamarine. It is currently h ...
*
Andamooka Opal
*
Flame Queen Opal
*
Galaxy Opal
*
Olympic Australis Opal
The Olympic Australis opal is the largest and most valuable opal yet found () and was valued at in 1997. It was found in 1956 at the 'Eight Mile' opal field near the town of Coober Pedy in South Australia.
The opal was found at a depth of . Th ...
References
Individual opals
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