crownedrose:

Stibnite is an awesome mineral, but also one that can be potentially toxic, so it must be handled with care (and always wash your hands!). It’s an antimony sulphide, Sb₂S₃, and also a soft mineral that comes in with only a 2.0 on the Mohs hardness scale. The specimen above is called “Spectacular Stibnite”, and the largest specimen ever displayed, and very rare due to its size/crystal structures. It’s also 1,000 pounds and originally from a Chinese mine.

This brilliant mineral was created around 130 millions years ago when antimony and sulphur were dissolved in water heated by volcanic activity, and then deposited between layers of limestone. For those beautiful crystals to grow so large, it would have been deposited in a pocket at one point, which is very lucky it was found and not destroyed while workers were in the mine.

It is on display at the American Museum of Natural History, New York, NY.
Photo credit: Ryan Somma on Flickr