The Collaborative International Dictionary of English v.0.48:

Shale \Shale\, n. [AS. scealy, scalu. See Scalme, and cf.
   Shell.]
   1. A shell or husk; a cod or pod. "The green shales of a
      bean." --Chapman.
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   2. [G. shale.] (Geol.) A fine-grained sedimentary rock of a
      thin, laminated, and often friable, structure.
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   Bituminous shale. See under Bituminous.
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The Collaborative International Dictionary of English v.0.48:

Bituminous \Bi*tu"mi*nous\, a. [L. bituminosus: cf. F.
   bitumineux.]
   Having the qualities of bitumen; compounded with bitumen;
   containing bitumen.
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         Near that bituminous lake where Sodom flamed. --Milton.
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   Bituminous coal, a kind of coal which yields, when heated,
      a considerable amount of volatile bituminous matter. It
      burns with a yellow smoky flame.

   Bituminous limestone, a mineral of a brown or black color,
      emitting an unpleasant smell when rubbed. That of Dalmatia
      is so charged with bitumen that it may be cut like soap.


   Bituminous shale, an argillaceous shale impregnated with
      bitumen, often accompanying coal.
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