rock alum

from The Collaborative International Dictionary of English v.0.48
Roche alum \Roche" al`um\ (Chem.)
   A kind of alum occuring in small fragments; -- so called from
   Rocca, in Syria, whence alum is said to have been obtained;
   -- also called {rock alum}.
   [1913 Webster]
    
from The Collaborative International Dictionary of English v.0.48
Rock \Rock\, n. [OF. roke, F. roche; cf. Armor. roc'h, and AS.
   rocc.]
   1. A large concreted mass of stony material; a large fixed
      stone or crag. See {Stone}.
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            Come one, come all! this rock shall fly
            From its firm base as soon as I.      --Sir W.
                                                  Scott.
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   2. (Geol.) Any natural deposit forming a part of the earth's
      crust, whether consolidated or not, including sand, earth,
      clay, etc., when in natural beds.
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   3. That which resembles a rock in firmness; a defense; a
      support; a refuge.
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            The Lord is my rock, and my fortress. --2 Sam. xxii.
                                                  2.
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   4. Fig.: Anything which causes a disaster or wreck resembling
      the wreck of a vessel upon a rock.
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   5. (Zool.) The striped bass. See under {Bass}.
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   Note: This word is frequently used in the formation of
         self-explaining compounds; as, rock-bound, rock-built,
         rock-ribbed, rock-roofed, and the like.
         [1913 Webster]

   {Rock alum}. [Probably so called by confusion with F. roche a
      rock.] Same as {Roche alum}.

   {Rock barnacle} (Zool.), a barnacle ({Balanus balanoides})
      very abundant on rocks washed by tides.

   {Rock bass}. (Zool.)
      (a) The stripped bass. See under {Bass}.
      (b) The goggle-eye.
      (c) The cabrilla. Other species are also locally called
          rock bass.

   {Rock builder} (Zool.), any species of animal whose remains
      contribute to the formation of rocks, especially the
      corals and Foraminifera.

   {Rock butter} (Min.), native alum mixed with clay and oxide
      of iron, usually in soft masses of a yellowish white
      color, occuring in cavities and fissures in argillaceous
      slate.

   {Rock candy}, a form of candy consisting of crystals of pure
      sugar which are very hard, whence the name.

   {Rock cavy}. (Zool.) See {Moco}.

   {Rock cod} (Zool.)
      (a) A small, often reddish or brown, variety of the cod
          found about rocks andledges.
      (b) A California rockfish.

   {Rock cook}. (Zool.)
      (a) A European wrasse ({Centrolabrus exoletus}).
      (b) A rockling.

   {Rock cork} (Min.), a variety of asbestus the fibers of which
      are loosely interlaced. It resembles cork in its texture.
      

   {Rock crab} (Zool.), any one of several species of large
      crabs of the genus {C}, as the two species of the New
      England coast ({Cancer irroratus} and {Cancer borealis}).
      See Illust. under {Cancer}.

   {Rock cress} (Bot.), a name of several plants of the cress
      kind found on rocks, as {Arabis petraea}, {Arabis lyrata},
      etc.

   {Rock crystal} (Min.), limpid quartz. See {Quartz}, and under
      {Crystal}.

   {Rock dove} (Zool.), the rock pigeon; -- called also {rock
      doo}.

   {Rock drill}, an implement for drilling holes in rock; esp.,
      a machine impelled by steam or compressed air, for
      drilling holes for blasting, etc.

   {Rock duck} (Zool.), the harlequin duck.

   {Rock eel}. (Zool.) See {Gunnel}.

   {Rock goat} (Zool.), a wild goat, or ibex.

   {Rock hopper} (Zool.), a penguin of the genus {Catarractes}.
      See under {Penguin}.

   {Rock kangaroo}. (Zool.) See {Kangaroo}, and {Petrogale}.

   {Rock lobster} (Zool.), any one of several species of large
      spinose lobsters of the genera {Panulirus} and
      {Palinurus}. They have no large claws. Called also {spiny
      lobster}, and {sea crayfish}.

   {Rock meal} (Min.), a light powdery variety of calcite
      occuring as an efflorescence.

   {Rock milk}. (Min.) See {Agaric mineral}, under {Agaric}.

   {Rock moss}, a kind of lichen; the cudbear. See {Cudbear}.

   {Rock oil}. See {Petroleum}.

   {Rock parrakeet} (Zool.), a small Australian parrakeet
      ({Euphema petrophila}), which nests in holes among the
      rocks of high cliffs. Its general color is yellowish olive
      green; a frontal band and the outer edge of the wing
      quills are deep blue, and the central tail feathers bluish
      green.

   {Rock pigeon} (Zool.), the wild pigeon ({Columba livia}) Of
      Europe and Asia, from which the domestic pigeon was
      derived. See Illust. under {Pigeon}.

   {Rock pipit}. (Zool.) See the Note under {Pipit}.

   {Rock plover}. (Zool.)
      (a) The black-bellied, or whistling, plover.
      (b) The rock snipe.

   {Rock ptarmigan} (Zool.), an arctic American ptarmigan
      ({Lagopus rupestris}), which in winter is white, with the
      tail and lores black. In summer the males are grayish
      brown, coarsely vermiculated with black, and have black
      patches on the back.

   {Rock rabbit} (Zool.), the hyrax. See {Cony}, and {Daman}.

   {Rock ruby} (Min.), a fine reddish variety of garnet.

   {Rock salt} (Min.), cloride of sodium (common salt) occuring
      in rocklike masses in mines; mineral salt; salt dug from
      the earth. In the United States this name is sometimes
      given to salt in large crystals, formed by evaporation
      from sea water in large basins or cavities.

   {Rock seal} (Zool.), the harbor seal. See {Seal}.

   {Rock shell} (Zool.), any species of Murex, Purpura, and
      allied genera.

   {Rock snake} (Zool.), any one of several large pythons; as,
      the royal {rock snake} ({Python regia}) of Africa, and the
      {rock snake} of India ({Python molurus}). The Australian
      rock snakes mostly belong to the allied genus {Morelia}.
      

   {Rock snipe} (Zool.), the purple sandpiper ({Tringa
      maritima}); -- called also {rock bird}, {rock plover},
      {winter snipe}.

   {Rock soap} (Min.), a kind of clay having a smooth, greasy
      feel, and adhering to the tongue.

   {Rock sparrow}. (Zool.)
      (a) Any one of several species of Old World sparrows of
          the genus {Petronia}, as {Petronia stulla}, of Europe.
      (b) A North American sparrow ({Pucaea ruficeps}).

   {Rock tar}, petroleum.

   {Rock thrush} (Zool.), any Old World thrush of the genus
      {Monticola}, or {Petrocossyphus}; as, the European rock
      thrush ({Monticola saxatilis}), and the blue rock thrush
      of India ({Monticola cyaneus}), in which the male is blue
      throughout.

   {Rock tripe} (Bot.), a kind of lichen ({Umbilicaria
      Dillenii}) growing on rocks in the northen parts of
      America, and forming broad, flat, coriaceous, dark fuscous
      or blackish expansions. It has been used as food in cases
      of extremity.

   {Rock trout} (Zool.), any one of several species of marine
      food fishes of the genus {Hexagrammus}, family {Chiradae},
      native of the North Pacific coasts; -- called also {sea
      trout}, {boregat}, {bodieron}, and {starling}.

   {Rock warbler} (Zool.), a small Australian singing bird
      ({Origma rubricata}) which frequents rocky ravines and
      water courses; -- called also {cataract bird}.

   {Rock wren} (Zool.), any one of several species of wrens of
      the genus {Salpinctes}, native of the arid plains of Lower
      California and Mexico.
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