- Mogul Tunnel Occurrence, Boulder Co. Tungsten District, Boulder Co., Colorado, USA
- Small Cabinet, 6.0 x 3.8 x 2.7 cm
A very rich sample of fine blue Ilsemannite on matrix from the Mogul Tunnel in Boulder County, Colorado. There is some question as to whether or not this Molybdenum oxide is a valid species, but I cannot find anything in the current literature to say whether or not it is valid or discredited. Nonetheless, specimens of this material are not seen on the market in any quantity, and this is certainly one of the finest pieces that I know of from Boulder County. Ex. Richard Kosnar Collection.