zirconoid

from The Century Dictionary.

• noun In crystallography, a double eight-sided pyramid belonging to the tetragonal system: so called because it is a common form with zircon.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Crystallog.) A double eight-sided pyramid, a form common with tetragonal crystals; -- so called because this form often occurs in crystals of zircon.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun crystallography A double eight-sided pyramid, a form common with tetragonal crystals; — so called because this form often occurs in crystals of zircon.