Akrochordite is a rare hydrated

arsenate mineral Arsenate minerals usually refer to the naturally occurring orthoarsenates, possessing the (AsO4)3− anion group and, more rarely, other arsenates with anions like AsO3(OH)2− (also written HAsO42−) (example: pharmacolite Ca(AsO3OH).2H2O) or (v ...

with the chemical formula and represents a small group of rare manganese (Mn) arsenates and, similarly to most other Mn-bearing arsenates, possess pinkish colour. It is typically associated with metamorphic Mn deposits.Handbook of Mineralogy
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References

Arsenate minerals Manganese minerals Monoclinic minerals Minerals in space group 14 {{Mineral-stub