Boulder Opal Sliced Pair. Queensland. Australia. ... (Total: 2 Items)

Description

Boulder Opal Sliced Pair
Queensland
Australia

This highly appealing pair of sliced and polished Boulder Opals was created when an Opal-bearing seam within an Ironstone concretion was split, revealing two complementary faces from the same formation. The Boulder Opal variety forms when Silica-rich solutions infiltrate natural cracks and cavities within Iron-rich Sandstone boulders, depositing precious Opal within the host matrix over long geological periods. The polished faces expose vibrant, expansive seams of precious Opal embedded within deep brown Ironstone, displaying electric flashes of violet, indigo, and cobalt blue that stand out dramatically against the earthy matrix. The opalization follows organic, vein-like patterns across each half, illustrating the original boulder's natural structure. The interior surfaces have been carefully cut and polished to highlight the Opal seam, while the exterior retains the natural Ironstone rind, creating an attractive contrast between the rugged host rock and the luminous interior. The richly colored matrix shows warm reddish-brown tones, and one half features a natural weathered cavity that adds dimension and visual interest. Portions of the Opal are semi-transparent, offering subtle windows into the stone. Material of this type is commonly sourced from the Boulder Opal fields of Queensland, Australia, a renowned locality for this variety. Presented as a matching pair, the specimen offers both strong display appeal and a clear illustration of the geological processes that form this distinctive type of precious Opal.
Large Half Measurements: 7.48 x 3.62 x 2.80 inches (19.00 x 9.20 x 7.10 cm)

Provenance: Austin Gem & Mineral Society

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