Hubnerite: Black Beauty

     Hubnerite is a black mineral whose crystals are flat rectangular prisms. Most of the examples that I’ve seen have front and back faces that are nearly perfect squares, but I’ve also seen a few that are more stretched out. Despite the way that I described it above, hubnerite is not always black. Actually pure hubnerite is reddish-brown or red and is translucent or transparent, but iron impurities can cause it to become black and lessen its translucency until it actually becomes opaque. Other impurities can give rise to other colors in hubnerite such as brownish-black, brownish-yellow, and brown. At one time hubnerite and another mineral called ferberite were thought to be the same mineral (this mineral’s name was wolfram.) Eventually scientists realized that the two were not the same mineral, but just very similar. Ferberite is composed of a chemical called iron tungstate and hubnerite is composed of manganese tungstate.
     Hubnerite is used as an ore of the metal tungsten. Tungsten is used to make steel alloys, the filaments in some incandescent light bulbs, and welding electrodes (the acronym TIG in TIG welding stands for “tungsten inert gas.”) Tungsten is also used to make a chemical called tungsten carbide, which is also known as “hardmetal.” True to its name hardmetal is very hard. I have used a knife sharpener that is made of hardmetal and have personally watched it peel stainless steel like a carrot! Hardmetal is also used to make scratch-resistant rings.
     Hubnerite is found in such places as: Peru, Mexico, Romania, Japan, Bolivia, Sweden, South Dakota, Washington state, North Carolina, New Jersey, and much of the Western U.S. Hubnerite has a place on my list of favorite minerals simply because of its unusual color and the fact that it contains tungsten, which few other minerals do!