In the outer silicate zone of alteration surrounding hydrated uranyl oxides incrusting primary uraninite; also filling fractures at some distance from primary uraninite.
IMA Status:
Valid Species (Pre-IMA) 1956
Locality:
In the USA, from the Delta mine, Emery Co., Utah; the New Method mine, near Amboy, San Bernardino Co., California. Link to MinDat.org Location Data.
Name Origin:
For Bertram Borden Boltwood (1870-1927), radiochemist of Yale University, New Haven, Connecticut, USA, who devised the U-Pb method of measuring geologic time.
Chemical Formula: 