Margarite is a calcium rich member of the mica group of the phyllosilicates with formula: CaAl2(Al2Si2)O10(OH)2.

It forms white to pinkish or yellowish gray masses or thin laminae.

It occurs commonly as an alteration product of corundum, andalusite and other aluminous minerals.

The margarite in this occurrence forms preferentially along the dark graphite rich inclusions with the chiastolite crystals.

Margarite is found in the emery deposits of Turkey and the Aegean islands, and with corundum at several localities in the United States.