Thank you so much for this identifying characteristic, I appreciate all the help I receive on this site! I recently purchased my first Refractometer and I can’t wait to see if it lines up with Hauyne, I think there’s a way to determine if the stone is singly or doubly refractive or birefringent using the refractometer, is that correct? I’m hoping to solve this mystery once and for all, although natural and man-made glass have properties that are extremely close if not overlapping with Hauyne’s. I may return for advice once I get time to play with my new “toy.” Thanks again and I will definitely post my results once I obtain them!
I looked through my collection after re-rereading your post, as I couldn’t shake the thought that I have something similar. I know the shape, and I organize some of the odd shaped stones in my collection by shape, and sure enough, I have some they are similar. These are “black” opals (I think that’s that term) from Australia (the location of last place origin I am certain of, it’s a secondary deposit and they are ancient so who knows where they may have come from). Although the colors are not quite the same, these were, sadly, stored in water before I got them and so they lost a lot of depth of color, but in water, they look nearly the sale. I also noticed what I think is a conoidal fracture type of your stone, which is consistent with opal, and I’m pretty sure opals have been found in that area. So my guess is opal. Let us know how it measures when you get a chance. Nice find, that’s for sure!
Note in the second pic the color of the opal from a side that was covered in muck and not exposed to water.
