Opal

specimen number:
1052707

location:
Bulla Creek, Queensland, Australia

description:
A beautiful piece of colorful older opal. This one historic in nature coming within old label as shown at the end of the video. This label is an original acquisition date of 1906.

The Bulla Creek opal field, situated along the Barcoo River basin in southwestern Queensland, Australia, is a classic, historic mining locality celebrated for producing high-grade precious boulder opal and unique gem-bearing siliceous ironstone nodules. Geologically, this historic deposit is located within the Late Cretaceous-age Winton Formation (historically referred to as the Desert Sandstone), where alternating beds of sandstone, siltstone, and mudstone underwent intense chemical weathering. Silica-rich groundwater percolated downward through these porous sedimentary strata during the Tertiary period, slowly precipitating as amorphous hydrous silica within the internal structural cracks, bedding planes, and hollow cavities of ironstone concretions to form rich veins of deep blue and multi-colored precious opal exhibiting intense red and green fire. Historically, localized hand-mining and primitive surface quarrying began following the initial mid-nineteenth-century exploration of the Barcoo region, with organized commercial operations rising to international prominence during the late 1880s and 1890s as the stone gained popularity in the European gem trade. Production at Bulla Creek reached its zenith around the turn of the twentieth century, but a combination of extreme outback droughts, severe water shortages, and the remote, hostile geography caused a steady decline, leading to the virtual abandonment of major corporate underground shaft workings by World War I. Through 2026, the area experiences intermittent, small-scale open-cut exploration and modern mechanical noodling by independent operators, and antique early twentieth-century specimens from Bulla Creek remain highly revered in historical mineral cabinets for their distinct geological setting and deep coloration.

Dr. Hugo Francke (1860-1933) was a prominent German mineralogist, chemist, and dealer based in Dresden who operated during the golden age of European mineral collecting. He is perhaps best known in the scientific community for having the rare sulfosalt mineral franckeite named in his honor in 1893 by the mineralogist Alfred Stelzner, following Francke's involvement with silver-tin ores from Bolivia. As a dealer, Francke was noted for his high-level scientific approach, often providing specimens to major university museums and private polymaths across Europe and North America. His catalogs from the late 19th century were highly regarded for their mineralogical accuracy, and his business was a key competitor to other major German houses of the era, such as those in Bonn or Berlin. Francke's labels are typically characterized by neat, formal German script or printing, often including the chemical formula and precise locality data, which was a hallmark of the Dresden school of mineralogy. After his death in the early 1930s, much of his remaining stock and personal research materials were absorbed into larger institutional collections, but specimens bearing his original provenance remain highly prized by historical collectors for their reliable documentation and academic quality.

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