1) Monoclinic mineral 
Akrochordite is an exceptionally rare hydrated hydrous arsenate mineral of the formula (Mn,Mg)4(AsO4)2(OH)4.4H2O and represents a small group of rare in the nature manganese (Mn) arsenates and, similarly to most other Mn-bearing arsenates, possess pinkish colour. It is typically associated with metamorphic Mn deposits. ...