Minerais e equivalentes sintéticos do sistema Fe2-O3-SO3-H2O

Abstract

The study of the Fe2-O3-SO3-H2O system needs revision because the papers concerning the subject stress either chemical or mineralogical aspects. The Fe(III)-sulfates occurring as minerais may be grouped in the following manner: a) Hydrogen-sulfates: Fe:S = 1:2 : rhomboclase*, "leucoglaucite". b) Sulfates ("normal"): Fe:S = 2:3 : quenstedtite, coquimbite*, paracoquimbite, kornelite*, lausenite*. c) Hydroxy- and oxy-sulfates: Fe:S = 7:9 : ferricopiapite*. Fe:S = 1:1 : fibroferrite, hohmannite, amarantite, butlerite*, parabutlerite, metahohmannite Fe:S = 3:2 : hydronium jarosite*. Fe:S = 4:1 : "glockerite". Fe:S = 8:1 a 16:3 : unnamed*. The minerais marked by an asterisk have been synthesized, and the products (H3O)Fe4(SO4)2, Fe2(SO4)3, Fe(OH)(SO4) and Fe4(OH)10(SO4) are known only as synthetic compounds. Minerais within quotation marks have been inadequately described. It is concluded that seven well characterized and two incompletely described minerais have not yet been synthesized. On the other hand, four compounds are known only as syntheüc products.