Compositional and Stability Relationships Among the Lithium Aluminosilicates: Eucryptite, Spodumene, and Petalite

The results of a phase‐equilibrium study of mixtures lying on the join eucryptite‐silica in the system LizO‐Al 2 O 3 –SiO 2 are presented. Hydrother‐mal techniques were used to obtain equilibrium relations among the crystalline phases at low temperature. The upper limits of stability of the naturally occurring forms of LiAlSiO, (eucryptite), LiA1SizO 6 (spodumene), and LiA1S i 4O 10 (petalite) were found to be 972°, 500°, and 680°c., respectively. Each of these minerals (low forms) was synthesized. An approximate diagram depicting equilibria among the phases is presented.