Aplowite

Aplowite is a very rare mineral with the formula CoSO₄•4H₂O, a naturally occurring cobalt(II) sulfate tetrahydrate. It is the lower hydrate when compared to bieberite (heptahydrate) and moorhouseite (hexahydrate), and a higher hydrate when compared to cobaltkieserite (monohydrate). It occurs together with moorhouseite within efflorescences.^[2][3]

Aplowite on a cobaltite crystal
General
Category	Rozenite
Formula	(Co,Mn,Ni)SO4 · 4H2O
IMA symbol	Apw[1]
Crystal system	monoclinic
Crystal class	Prismatic - 2/m
Identification
Color	bright pink, light pink in light
Mohs scale hardness	3
Luster	Vitreous (Glassy)
Streak	white
Diaphaneity	transparent
Density	2.33 g/cm3 (Measured) 2.36 g/cm3 (Calculated)
Optical properties	Biaxial (–). α = 1.528 β = n.d. γ = 1.536
2V angle	n.d.
Solubility	soluble in water
References	[2]