History · Geology
About Lightning Ridge
Lightning Ridge in northern New South Wales, Australia, is the world’s only commercial source of premium black opal — the rarest and most valuable variety of precious opal. Mining has been active since 1903.
Geology
The opal occurs in Cretaceous sandstones of the Griman Creek Formation. Hydrated silica precipitated in fissures and replaced fossil bones and shells, producing both seam opal and “opalized fossils” of dinosaur-age origin.
Notable Material
Black precious opal (the highest-value gem variety, with brilliant play-of-color against a black body tone), opalized wood, opalized fossil bone, and rare opalized vertebrate remains. The “Halley’s Comet” black opal (1986) remains the largest known single piece.
Collector Notes
Lightning Ridge premium gem-grade black opal commands $20,000+/carat at top tier — among the highest priced of all gemstones. Mining is small-scale and unique to this locality.
Minerals Produced Here
- Opal (蛋白石)
