Boltwoodite - Sold
- Rössing mine
- 5.1 by 4.4 by 2.1 cm – Miniature specimen (fits into a 5 cm cube)
Orange needles of boltwoodite form radiating sprays to 6 mm across on a bed of smoky calcite crystals. Boltwoodite is an ore mineral at the Rössing mine, one of the largest producers of uranium in the world. Frondel & Ito (1956) named boltwoodite in honor of Bertram Borden Boltwood (1870–1927), radiochemist of Yale University, New Haven, Connecticut, USA, who devised the U-Pb method of measuring geologic time. Studies by Stohl & Smith (1981) and Burns (1998) have defined the formula of boltwoodite: K(UO2)(SiO3OH)·1.5H2O. Burns (1998) noted a substantial sodium content to his Rössing sample.