Serpierite
Serpierite (Ca(Cu,Zn)4(SO4)2(OH)6·3H2O) is a rare, sky-blue coloured hydrated sulfate mineral, often found as a post-mining product. It is a member of the devilline group, which has members aldridgeite (Cd,Ca)(Cu,Zn)4(SO4)2(OH)6·3H2O, campigliaite Cu4Mn(SO4)2(OH)6·4H2O, devilline CaCu4(SO4)2(OH)6·3H2O, kobyashevite Cu5(SO4)2(OH)6·4H2O, lautenthalite PbCu4(SO4)2(OH)6·3H2O and an unnamed dimorph of devilline. It is the calcium analogue of aldridgeite and it is dimorphous with orthoserpierite CaCu4(SO4)2(OH)6·3H2O.