From the Merck Index:
8715. Sodium Aluminate.
Aluminum sodium oxide. AlNaO2; mol wt 81.97. Al 32.92%, Na 28.05%, O 39.04%. White granular mass. mp 1650 deg. Very sol in water. Insol in alcohol.
The aq soln is strongly alkaline.
USE: Printing on fabrics; manuf lake colors; sizing paper; manuf milk-glass, soap; hardening building stones; water softener.