Scarbroite, Al5(OH)13CO3·5H2O, Compared with Gibbsite and Hydrotalcite

G. W. Brindley
Mineral Sciences Building, Pennsylvania State University, University Park, PA 16802, USA

Summary: The composition of scarbroite, written in the form Al5(OH)13CO3·5H2O, suggests close crystal-chemical relations to gibbsite and to hydrotalcite and kindred minerals. Parametral relations a(S) ≃ 2b(G) and 3b(S) ≃ 5a(G), S = scarbroite, G = gibbsite, are obtained and are consistent with a hydroxy Al layer structure and interlayer carbonate anions and water molecules. Thermal transformations show two discrete hydrated phases with layer spacings near 8.5 and 7.65 Å and a third phase with initial spacing 6.65 Å which decreases progressively to 5.5 Å over the temperature range 100°–250 °C as decomposition proceeds. No clear break is observed between dehydroxylation and decarbonation.

Mineralogical Magazine; March 1980 v. 43; no. 329; p. 615-618; DOI: 10.1180/minmag.1980.043.329.08
© 1980, The Mineralogical Society
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