Here is a beautiful cabochon of this very hard to find material, from a short lived discovery.

Much of this material had visible fractures and flaws, so finding pieces clean enough and stable enough to properly cab can be a challenge for sure.

As seen in the photos, this cab does have an internal fracture flaw, but does not reach the surface and is very stable. That is why the price is much lower on this beauty!

Some refer to it as a Black Rainbow Sunstone or Black Moonstone due to it's adularescence, either way it is a form of feldspar and is beautiful no matter what you call it! 

Discovered a few years ago, this material in the rough, looks black in color with streaks of iridescent hematite running through it.

The hematite streaks look similar to the Australian Rainbow lattice, except for the material color and that very little of this material was found to have a lattice pattern.

Also, the hematite bands in this material run completely through it and not just in layers, in one photo of the rear of the piece, you can see where the hematite reaches the surface.

When cut and polished the "black" color looks more brown when light is able to pass through it, but mounted, it will appear almost black.