It can occur naturally, and I would assume this is a natural one because it was in an excellent museum where they probably would have mentioned if it was altered.
Basically, when it’s found, it’s usually yellow, but as the copper and iron in the mineral react with oxygen and moisture over time, it develops a thin iridescent tarnish.
Looks like it was hit with a blowtorch. Can this even occur naturally?
It can occur naturally, and I would assume this is a natural one because it was in an excellent museum where they probably would have mentioned if it was altered.
Basically, when it’s found, it’s usually yellow, but as the copper and iron in the mineral react with oxygen and moisture over time, it develops a thin iridescent tarnish.