ironstone

One Yowah nut, bisected

One of many opal mining sites in the red continent is called Yowah, and is famous for its opal nuts, veins of precious glowing opal within nodules of siliceous ironstone that often form amazing patterns. They vary from 0.5 to 20 cm across, and occur in an iron rich sandstone, near the border with an adjoining mudstone.

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Boulder opal

The beautiful slice depicted in the photo is made of precious opal in ironstone matrix, replacing a small branch of fossilised wood. The fractures in the wood infiltrated by the silica gel are clearly visible in this beautiful piece from Australia measuring 28 x 22 x 5mm.

Loz


Image credit: Planter opal on etsy.

Yowrah nut cabochon

These beautiful Australian opal nuts consist veins of precious glowing opal within nodules of siliceous ironstone that often form amazing patterns. They vary from 0.5 to 20 cm across, and occur in an iron rich sandstone, near the border with an adjoining mudstone. This one has been sliced and polished into cabochons, revealing the intricacy of the patterns of the gemmy silica within.

Loz

Image credit: J.J. Harrison