a. A rounded rock fragment of any size larger than a sand grain; a group
name for pebbles, cobbles, or boulders -- any or all of these.
b. A diamond crystal with an arched facet. Hess
c. A term proposed by Fernald (1929) for any naturally rounded rock
fragment of any size larger than a sand grain (diameter greater than 2
mm), such as a boulder, cobble, pebble, or granule.
See also: cobblestone
Dictionary of Mining, Mineral, and Related Terms