What does "pebble" mean?

Pebble: Transparent and colorless rock crystal; as, Brazilian pebble; -- so called by opticians. Pebble powder, slow-burning gunpowder, in large cubical grains. -- Scotch pebble, varieties of quartz, as agate, chalcedony, etc., obtained from cavities in amygdaloid.

Additional senses

  1. 2.To grain (leather) so as to produce a surface covered with small rounded prominences.

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