What is "scotch pebble"

Pebble \Peb"ble\, n. [AS. papolst[=a]n; cf. L. papula pimple, mote. See Stone.]

1. A small roundish stone or bowlder; especially, a stone worn and rounded by the action of water; a pebblestone. ``The pebbles on the hungry beach.''
   --Shak.

   As children gathering pebbles on the shore.
   --Milton.

2. 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.

Scotch \Scotch\, a. [Cf. Scottish.] Of or pertaining to Scotland, its language, or its inhabitants; Scottish.

Scotch broom (Bot.), the Cytisus scoparius. See Broom.

Scotch dipper, or Scotch duck (Zo["o]l.), the bufflehead; -- called also Scotch teal, and Scotchman.

Scotch fiddle, the itch. [Low]
--Sir W. Scott.

Scotch mist, a coarse, dense mist, like fine rain.

Scotch nightingale (Zo["o]l.), the sedge warbler. [Prov. Eng.]

Scotch pebble. See under pebble.

Scotch pine (Bot.) See Riga fir.

Scotch thistle (Bot.), a species of thistle ( Onopordon acanthium); -- so called from its being the national emblem of the Scotch.