from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A form of crystal resembling quartz, having two six-sided pyramids, base to base.
from the GNU version of the Collaborative International Dictionary of English
- n. A form of crystal common with quartz, consisting of two six-sided pyramids, base to base.
from The Century Dictionary and Cyclopedia
- In crystallography, a double six-sided pyramid, represented by uniting two six-sided single pyramids base to base.
quartz + -oid (Wiktionary)