The uranium workings at the south end of Calf Mesa in Emery County, Utah (the Dexter Group of claims)  have produced some of the more unusual and attractive sulphates known from the Western U.S.  Workings develop uranium mineralization in sandy units in the Chinle Formation of Triassic Age. While specimen production during actual development of the properties in the 1950’s thought to have been minor, abundant specimens were found as secondary accumulations in waste rock at the mines in the late 1980’s. There has been more recent collecting of specimens there but the extent of that activity is unknown. Because many of the minerals of interest at the Dexter Group are formed in waste rock and ores exposed to weathering there may be a continuing opportunity for collecting good specimens there for some time.