Sulphate of Iron and Argilla Enlarge
[Undated]
Exotic Mineralogy
CXLVI
Ferrum sulphatum, Argilliferum

Sulphate of Iron and Argilla

Sulphate of Iron is the common produce of the decomposition of rocks containing Iron Pyrites, and probably often contains Sulphate of Argilla; in which case it seems sometimes to have been taken for native Alum, although it wants the Alcali. The specimen before us is from Bacherstolln, in Schmölniz: it contains a considerable quantity of Argilla, but apparently no Alum; which is, however, readily produced from it, by adding a little Potash. Its sourer taste distinguishes it from pure Sulphate of Iron: it is also less astringent, and less liable to be acted upon by the atmosphere.

The specimen was lent me by H. Heüland, Esq. whose uncommon liberality deserves my warmest thanks.

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