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Coocoran Opal Fields, Lightning Ridge, Finch Co., New South Wales, Australia

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Latitude & Longitude (WGS84): 29° 27' 48'' South , 147° 45' 39'' East
Latitude & Longitude (decimal): -29.46333,147.76083
Köppen climate type:BSh : Hot semi-arid (steppe) climate

The Coocoran opal fields consist of about 50 named opal fields are located about 21 kilometres east of the town of Lightning Ridge. A "field" is an area where opal mineralisation has been found. Locally an opal field is known as a "rush" and is often named after the opal miner that initially found mineralisation in that area.

On the Coocoran opal fields a rush can range in area from about 1 hectare up to more than 20 hectares. Peak production occurred in the period from late 1980s to late 1990s.

Underground and open cut mining techniques are used to extract opal from depths ranging from near surface up to 25 metres underground. The host rock is the Cretaceous Griman Creek Formation which is predominantly composed of freshwater (rarely estuarine?) claystones and sandstones.

Most gem opal from the Coocoran opal fields is found as "nobby" opal. Nobby opal occurs as spheroidal or disc like pieces of opal that range from about 1 to 15cm in diameter sporadically distributed through claystone layers.

Opalised fossils also occur sporadically. Fossils include bivalve shells, gastropod shells, dinosaur bones & teeth, turtle shell & bones, crustacean gastroliths, plant stems & fruiting bodies, plesiosaur bones & teeth, monotreme bones, etc.

Mineral List

Mineral list contains entries from the region specified including sub-localities

1 valid mineral.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on

0 - 66 Ma

ID: 871117
sedimentary rocks 72357

Age: Cenozoic (0 - 66 Ma)

Description: Undifferentiated consolidated Cenozoic sedimentary rocks; sandstone, limestone, conglomerate, siltstone, duricrust; commonly ferruginised or silicified; may be poorly consolidated, highly weathered, and dissected by present day drainage.

Comments: sedimentary siliciclastic; regolith; synthesis of multiple published descriptions

Lithology: Sedimentary siliciclastic; regolith

Reference: Raymond, O.L., Liu, S., Gallagher, R., Zhang, W., Highet, L.M. Surface Geology of Australia 1:1 million scale dataset 2012 edition. Commonwealth of Australia (Geoscience Australia). [5]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

Localities in this Region

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


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Aracic, Stephen (1999), Rediscover Opals in Australia, published 1999 by the Kingswood Press.
Smith, E. & R. (1999): Black Opal Fossils of Lightning Ridge - Treasures from the Rainbow Billabong, Kangaroo Press, East Roseville.
Cram, L. (2004): A Journey with Colour, Vol 2, Part B - A History of Lightning Ridge Opal 1873-2003, Len Cram.

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