perimorphism

per·i·morph

 (pĕr′ə-môrf′)
n.
A mineral that encloses a different mineral.

per′i·mor′phic, per′i·mor′phous adj.
per′i·mor′phism n.

perimorphism

a phenomenon in which one mineral encloses another. — perimorphic, perimorphous, adj.
See also: Geology