No, I did not scoop this out of a cat's litter box (nothing like a tasteful sales pitch...) This is an exceptionally large crystal of painite-- crystals 2 cm are hard enough to find, this thing is a monster at 4.6. As with the vast majority of these, the surfaces have heavy etching/ inclusions, but it does retain decent overall form-- and even a rough termination.
Up until several years ago, this rare borate was touted as the world's rarest gemstone, with fewer than 20 carefully documented crystals having been collected since its discovery in the 1950's. Then in late 2005, the source was discovered, and they were finally made available to collectors.
If you wanted something larger than a thumbnail, this is a very, very rare opportunity to get one. I've never handled one larger, and it is among the 2 or 3 largest from those pictured on Mindat.
It may look like a chocolate bar that's been lost in a sofa for years, but it's a good rock.