gypsum
Concise Oxford English Dictionary © 2008 Oxford University Press:
gypsum /ˈdʒɪpsəm/
▶noun a soft white or grey mineral consisting of hydrated calcium sulphate, used to make plaster of Paris and in the building industry.
– derivatives
gypsiferous /-ˈsɪf(ə)rəs/ adjective.
gypsiferous /-ˈsɪf(ə)rəs/ adjective.
– origin ME: from L., from Gk gupsos.
'gypsum' also found in these Oxford entries:

