I bought the rough material at a "Rock Gem 'n' Bead" show in Edinburgh and polished it at the Scottish Mineral & Lapidary Club. It's likely from Argentina, but I can't be sure. Below is the chunk I bought, before the sphere was cut out of the right side.

The cleaved crystal structure also posed a threat to parts flaking off. I had an issue with this in the initial shaping, but it managed to hold together beyond that.  It was relatively quick to polish given its softness on the Mohs scale (3.5-4), but there was however slight undercutting due to the banding in the material. This required a while on the finer grade grits to really bring it down it down before the polish.