Crystal System: Trigonal
Status of Occurrence: Unconfirmed Occurrence
Chemical Composition: Ammonium iron sulphate hydroxide
Chemical Formula: NH4(Fe3+)3(SO4)2(OH)6
Method(s) of Verification: XRD at the National Museum of Wales (XRD no. NMW X-1775). Some form of chemical analysis is desirable before definitive identification is made.
- Supergene: post-mining oxidation & weathering deposits
Introduction: a secondary iron sulphate mineral formed by the decay of pyrite, particularly in dark shales.
Occurrence in Wales: ammoniojarosite has tentatively been identified intimately associated with copiapite and gypsum in ocherous yellow crusts on a sample (National Museum of Wales collection, no. NMW 85.14G.M.64) picked up from the dumps of an old iron mine near Taff's Well in South Wales.
There are no key localities for this specimen.
There are no references for this specimen.