I grew some Chalcanthite crystals in a copper nitrate solution about a year ago. They've just been sitting on a shelf ever since. The previously bright blue color and euhedral crystal faces are starting to fade and decay. I just recently bought a small, clear glass box with a rubber seal to hopefully keep it from dehydrating further. Is there something else I can do to slow the decay? Someone suggested that I soak it or rub it with mineral oil. Is this a good or bad idea?
Thank you in advance.