Formation
(1) Primarily magmatic, formed by fractional crystallization as an accessory mineral in granitic pegmatites and S-type granites.
(2) Hydrothermal, formed by precipitation in vein ore deposits.
(3) Sedimentary, formed by U precipitation under reducing, anoxic conditions (e.g. in sandstones)
(4) Due to its high mechanical and chemical resistance, found in alluvial placer deposits
