agate

English Thesaurus

1. an impure form of quartz consisting of banded chalcedony; used as a gemstone and for making mortars and pestles (noun.substance)

hypernym	:	calcedony, chalcedony,
definition	:	a milky or greyish translucent to transparent quartz (noun.substance)

hyponym	:	moss agate,
definition	:	an agate resembling moss with brown, black, or green markings (noun.substance)