Spodumene is the current principal commercial source of lithium for chemical manufacture and occurs in the greatest abundance of the four main lithium ores. It has a greater lithium content than either lepidolite or petalite. The chemical formula for spodumene is LiAlSi2O6. Theoretically it contains 3.75% lithium (8.04% lithia). The ore is concentrated by a flotation process to yield a product with 2.8-3.3% lithium (6-7% lithia), since it normally occurs mixed with other minerals. Large spodumene deposits are found in the United States, Canada, Brazil, Argentina, the USSR, Spain and the Congo.
Spodumene, a monoclinic pyroxene, may be thought to have a structure of -S1O3- chains bonded together by lithium and aluminum ions
4 . When α-spodumene, the naturally occurring mineral, is heated to about 1000°C, an irreversible phase transition occurs to yield β-spodumene. The phase transformation is accompanied by a large increase in volume. The density of a-spodumene is about 3.2 g c m
-3 ; that of β-spodumene about 2.4 g cm
-3.
