So my friend brought this crystal home that her brother gave her. It's fairly heavy I'd say around three pounds. Her brother told her that it was a byproduct of copper or was synthesized from it. Whether or not I can go by that I do believe it's TRUE just because of the green covering a lot of the outside of the crystal.

Initially I thought it might be Azurite but I've done a water solubility test and tiny pieces did indeed dissolve in the warm water. This leaves me thinking its chalcanthite but I'm not 100% sure.

Any other easy tests I can do to verify its chalcanthite or am I right on the money?