Lavendulan

Lavendulan is an uncommon copper arsenate mineral, known for its characteristic intense electric blue colour. It belongs to the lavendulan group, which has four members:

Lemanskiite and lavendulan are dimorphs; they have the same formula, but different structures. Lemanskiite is tetragonal, but lavendulan is monoclinic. Lavendulan has the same structure as sampleite, and the two minerals form a series. It is the calcium analogue of zdenĕkite, and the arsenate analogue of sampleite.