MA spinel does not occur in nature and so commercial powders have to be synthesized
using a wide variety of techniques. The oldest, simplest, and still most
widely used method is the conventional oxide mixing (CMO), or solid–solid
reaction, technique. With this technique, powdered MgO- and Al2O3-bearing
compounds (e.g., oxides, hydroxides, or carbonates) are mixed and pressed
into pellets or some other shapes and then heated in a furnace at high temperature
for prolonged periods. After synthesis, the product mass is crushed to aggregates
or further ground to powders with the desired size distribution.