https://broadstoneminerals.com/species/langite/
Langite | The Copper Sulphate That Formed After Mining
Langite is a hydrated copper sulphate, hardness 2.5 to 3, crystals to 7 mm. It can form on mine walls and dumps after the workings closed, so it postdates them.
the copperlangitesulphateformedmining