Location: New Mexico
Here's a very interesting new addition to the mineral collection at the Sholesonian. This is known as Pyrolusite, and despite it's small size it is different from all the other specimens. Pyrolusite comes in a variety of forms such as botryoidal, columnar and tabular but this is the common black fibrous form. Coming from New Mexico this mineral consists of Manganese and Oxygen (MnO2) making it an oxide mineral.
"A common Mn mineral, although difficult to distinguish from similar Mn minerals, pyrolusite forms under oxidizing conditions and high pH. Mainly a mineral of lacustrine, shallow marine, and bog deposits, it is also found in the oxidized zones of manganiferous ore deposits and as deposits formed by circulating meteoric water. Both colloidal processes and bacterial action are important in its formation."
It can have a wide range of hardness on Moh's Scale ranging from 2 to 6.5. The name pyrolusite comes from Greek, meaning fire (pyro) and wash (lusite), which is named such in its use to remove tints from glass.
This mineral also had a hand in the discovery of chlorine gas. When applied with hydrochloric acid the mineral reacts with the acid and produces chlorine gas as a product. Other uses include making a battery (albeit not a very powerful one) and as a dye.