Opal

specimen number:
1052678

location:
Bulla Creek, Queensland, Australia

description:
Fine antique polished opal specimen from Australia. The specimen comes with an antique label as shown in the picture and video. Original acquisition date was 1908.

The Bulla Creek opal field, located in the Eromanga Basin of Queensland, Australia, is a significant locality for boulder opal within the Winton Formation. Geologically, the deposit consists of Cretaceous sedimentary rocks where silica-rich groundwater percolated through weathered sandstone and ironstone, depositing precious opal within the voids, fractures, and ironstone concretions (locally called "nuts"). This process created the characteristic boulder opal, where thin veins of vibrant, play-of-color opal are naturally bonded to a dark ironstone matrix. Historically, mining and quarrying in the Bulla Creek area began in the late 19th century, with a notable increase in activity following the broader Queensland opal rush of the 1890s. Unlike the large-scale open-cut operations seen in other districts, Bulla Creek has traditionally been worked by small teams and individual prospectors using bulldozers and excavators to strip the overburden and expose the opal-bearing layers. While production has fluctuated over the decades due to the remote, arid conditions and the erratic nature of the pockets, the field remains an active source of high-quality specimen and gemstone material through 2026. The site is particularly valued by collectors for its deep ironstone contrast and unique patterns, representing a classic example of Australian sedimentary opal formation.

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