a variety of chalcedony with dark greenish mossy markings, used as a gemstone
moss agate in American English
a kind of agate containing dark-colored, branchlike markings of manganese or iron oxides
moss agate in American English
noun
a kind of agate or chalcedony containing brown or black mosslike dendritic markings from various impurities
Word origin
[1790–1800]This word is first recorded in the period 1790–1800. Other words that entered Englishat around the same time include: echelon, gelatin, idealism, infiltration, silhouette