cre'ta

[L.] Chalk, calcium carbonate, c. gal'Iica, French chalk, a magnes i tun silicate harder than talc. c. prsepara'ta (U.S. and Br.), prepared chalk, purified native calcium carbonate, a grayish white amorphous powder, usually moulded into cones; employed as a mild astringent and antacid, in doses of gr. 10-30 (0.6-2.0).