Paramontroseite (VO2) a relatively rare mineral in the Ramsdellite group that has anomalously radioactive masses mostly caused by specks of a uranium-bearing, silicate mineral called coffinite that occurs as black incrustations that is found in a few places in the USA, such as Fall River County, South Dakota, that is named for Fall River that runs through it.
Paramontroseite (VO2) is a relatively rare orthorhombic vanadium oxide mineral in the Ramsdellite group. The masses are anomalously radioactive and the surrounding sandstone is weakly radioactive. The radioactivity is mostly caused by tiny specks of coffinite in the paramontroseite. Coffinite is a uranium-bearing silicate mineral with formula: U(SiO4)1x(OH)4x. It occurs as black incrustations, dark to pale-brown in thin section. In the USA it is found in Montrose County, Colorado, San Miguel County, Colorado, Mesa County, Colorado, Emery County, Utah, Apache County, Arizona, McKinley County, New Mexico and Fall River County, South Dakota. It is named for Fall River which runs through it. 
