Opal

specimen number:
1052624

location:
Barcoo River, Barcoo Shire, Queensland, Australia

description:

Very attractive example of colorful Boulder opal. Fine antique example, this comes with an old label as seen in the picture and video. The acquisition date on this label is 1910.

The Barcoo River region, situated within the vast Eromanga Basin of central Queensland, Australia, is a primary source of the world-renowned boulder opal. Geologically, these deposits formed during the Cretaceous period when silica-rich fluids permeated the cracks and ironstone concretions of the Winton Formation, a sedimentary sequence consisting of sandstones and mudstones. The opal occurs as precious "precious opal" or common "potch" within the matrix of dark brown ironstone boulders, characterized by vibrant flashes of color against a dark background. Historically, mining and quarrying in the Barcoo district began in the late 1800s, with significant rushes occurring around 1888 near localities such as Blackall and the Hayricks. Unlike the large-scale open-cut operations found in other Australian fields, the Barcoo deposits are often worked by small teams of independent miners using heavy machinery to unearth the scattered boulders from the desert soil. While production has fluctuated due to extreme environmental conditions and the remote nature of the terrain, the area remains an active and vital producer of high-quality boulder opal. Today, the Barcoo River remains a symbol of the rugged Australian opal industry, with prospecting and extraction continuing to yield unique specimens through 2026.

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