plagioclastic
/ˌpleɪdʒɪə(ʊ)ˈklastɪk/Mineralogy
adjective
Designating or characterized by feldspars which have crystal cleavages at an oblique angle to each other; relating to or of the nature of plagioclase.
Origin
Mid 19th century. From plagio- + -clastic, after plagioclase.