Rock butter

Rock butter (also known as stone butter) is a soft mineral substance found oozing from alum slates.

It consists of native alum mixed with clay and oxide of iron, usually in soft masses of a yellowish white colour[1] with translucent edges,[2]: 307  occurring in cavities and fissures in argillaceous slate.

This substance hardens when exposed to air, but softens if the air is humid enough.[3]: 28  The texture is sometimes described as "greasy".[2]: 307 

It was referred to as "rock butter" in English as early as 1816.[2]: 306–7 

It has been recorded in various locations around the world, including Paisley, Scotland; Bornholm, Denmark; Bad Muskau in Germany; and along the Yenisey in Siberia.[2]: 307  An 1837 article noted that at the "Kiffhäusen" stone quarries in Germany, the workmen called it steinbutter and ate it spread on bread.[4]: 37 

There have been reports of people eating rock butter in various parts of the world, including Siberia,[3]: 28  Germany, and Austria.

See also

References

  1. ^ [1], from the U.S. Bureau of Mines' Dictionary of Mining, Mineral, and Related Terms (1996), online at the Hacettepe University Department of Mining Engineering website.
  2. ^ a b c d Jameson, Robert (1816). System of Mineralogy (PDF). Vol. 2. London: Longman, Hurst, Rees, Orme & Brown; Edinburgh: Neill for A. Constable & Co. ISBN 1108029744. Retrieved 24 March 2025. {{cite book}}: ISBN / Date incompatibility (help)
  3. ^ a b "Sketch of the Geology of the Arctic Regions" (PDF). The American Journal of Science and Arts. 17. 1830 – via Wikimedia Commons.{{cite journal}}: CS1 maint: url-status (link)
  4. ^ Murray, John (15 January 1837). "Conversations on Nature and Art" (PDF). The Examiner. pp. 36–37. Retrieved 14 May 2025.{{cite news}}: CS1 maint: url-status (link)


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