The Collaborative International Dictionary
Quartzoid
Quartzoid \Quartz"oid\, n. [Quartz + -oid.] (Crystallog.) A form of crystal common with quartz, consisting of two six-sided pyramids, base to base.
Wiktionary
quartzoid
n. (context mineralogy English) A form of crystal resembling quartz, having two six-sided pyramids, base to base.