Mullite

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Mullite, or porcelainite, is a rare clay mineral with the chemical composition Al₆Si₂O₁₃, a form of aluminium silicate. It is produced artificially during various melting and firing processes, and is used as a refractory.^{[citation needed]}

In 2006 researchers at University College London and Cardiff University discovered that potters in the Hesse region of Germany since the late Middle Ages had used mullite in the manufacture of a type of crucible (known as Hessian crucibles), that were renowned for enabling alchemists to heat their crucibles to very high temperatures.^[1] The formula for making it (using kaolinitic clay and then firing it at temperatures above 1100 degrees Celsius) was kept a closely guarded secret.

Mullite is present in the form of needles in porcelain.^[2]

[edit] Notes

[edit] References

• Martinón-Torres, Marcos; Thilo Rehren and Ian C. Freestone (November 2006). "Mullite and the mystery of Hessian wares" (PDF online reproduction). Nature 444 (7718): pp.437–438. London: Nature Publishing Group. doi:10.1038/444437a. ISSN 0028-0836. 
• Schneider, Hartmut (2005). "General Introduction", in Hartmut Schneider and Sridhar Komarneri (eds.): Mullite. Weinheim, Germany: Wiley-VCH, xv–xx. ISBN 978-3-527-30974-0. OCLC 58051400. 
• University College London (2006-11-23), “21st Century Technology Cracks Alchemists' Secret Recipe”, ScienceDaily, <http://www.sciencedaily.com/releases/2006/11/061123120134.htm>. Retrieved on 2008-01-12