Australian opal with dendrites

[Craig]

Hello all was cutting some opal again today and I cut this little guy. 1.7 carats and I believe it has dendrites in it and I've never seen it in Australian Opal. Or am I just sheltered? Lol
any feedback would be appreciated

[SwordfishMining]

Hiya. Thats neat looking. I cant say I've run across a picture like that before. But manganese does like to make dendrites and i was lead to believe white opal was opaque because of manganese oxide or something like that with iron or manganese as what made black opal black too & I think it maybe also attributes the UV glow to that.
But we have a lot of sulfur here in volcano lands around the world making sulfides which are not the best in the stability mix. Somewhere I read desert varnish was a variety of air deposited black opal.
Thanks for sharing that one.

[OpalSpectrum]

Hi Craig , I think this is 'black potch webbing' which sometimes can form odd shapes inside the crystal opal > like in your example
*some Lightning Ridge opals have a lot of potch webbing very similar to Ethiopian opals - I might create post about it

here are some similar crystals which I've cut couple years ago ?





hope this helps