mountain soap

English

Noun

mountain soap (uncountable)

1. (possibly obsolete) A soft earthy mineral, of a brownish colour, which has a greasy or soapy feel and is used as a filler in crayons.
   • 1805, Robert Jameson, A Treatise on the External Characters of Minerals, page 76:

     It soils either strongly, as chalk and mountain soap; or slightly, as molybdana, lead glauce, and graphite. Besides this, there are three other distinctions connected with this character to be attended to.

   • 1848, American Journal of Science and Arts, page 72:

     […] seven different minerals possessing the same formula, namely, fahlunite, esmarkite, pyrargillite, bole, iron lithomarge, halloylite from La Vouth and from Thiviers, and mountain soap from Thuringia.

   • 1859, Gustav Bischof, Elements of Chemical and Physical Geology ..., page 311:

     Sometimes, after removing the coating of calcspar from the crystals, they appear to be covered with a mass resembling steinmark or mountain soap. The compact and crystalline hornblende occurs almost everywhere as a constituent of the […]

Synonyms

• rock soap
• saponite

References

• “mountain”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• “mountain soap”, in OneLook Dictionary Search.