Category Arsenate mineral Strunz classification 8.BE.30 Space group P21/a | Formula
(repeating unit) Mn7(AsO4)2(OH)8 Crystal system Monoclinic | |
 | ||
Crystal class Prismatic (2/m)
(same H-M symbol) | ||
Allactite is a rare arsenate mineral of metamorphosed manganese zinc ore deposits. It is found in Sweden and New Jersey, US. Its name originated from Greek αλλάκτειν (allaktein) meaning "to change", referring to the strong pleochroism of the mineral.
References
Allactite Wikipedia(Text) CC BY-SA