Pulitzer Opal on Digit Patterns in Australian Opal

[SwordfishMining]

1,143 views Apr 17, 2024

The digit pattern in precious opal, particularly notable in Australian opal, is a rare and striking phenomenon characterized by finger-like structures within the gemstone. These structures, resembling fingers or digits, were first documented in a 2013 article in Gems and Gemology by French authors, who termed it the "digit" pattern. The pattern evolves into a net-like honeycomb pattern at the surface, adding to its allure. Justin Thomas of Black Opal Direct notably discovered a large example of this pattern, named the "Rainbow Serpent," in 2016. While this pattern is more commonly observed in Ethiopian opal, its occurrence in Australian opal is relatively scarce.

The formation of these finger-like structures, termed prismatic photonic colloidal crystals by Australian gemologists, is believed to be the fundamental process behind all precious opal formation. Despite the beauty of synthetic opals, their distinct columnar patterns and lack of natural variation distinguish them from genuine opals. The intricate process of opal formation involves the deposition of colloidal silica within sedimentary rock, resulting in the formation of columns of opal that are often disrupted by subsequent silica flows. However, some opal seams, such as those found in Coober Pedy and Andamooka, manage to preserve the delicate columnar structures, contributing to their rarity and value.


I don't know what John Sinkankis called it when he was here collecting, but Virgin Valley Opals are the biggest examples of it size wise.

[OpalSpectrum]

i was going to post this

glad he made it because we been talking about the 'diggit/column/tubes' for years !

Ribbon - Stripe - Plume - Fern > all this pattern are actual type of 'Digit' formation

viewtopic.php?p=5019&hilit=tubes#p5019
viewtopic.php?p=6643&hilit=tubes#p6643
viewtopic.php?p=787&hilit=digit#p787
viewtopic.php?p=25280&hilit=digit#p25280

here 1 on my favorite examples (from the collection) which I posted couple years ago