A large cabinet example of reddish orange orpiment from Peru. I have sprayed this with a UV absorber to help preserve it-- it doesn't really change the appearance of the specimen.
A side note: A couple Peruvian dealers were spraying their realgars with hairspray, and were seeing positive results in terms of longer term preservation-- it turns out that some hairsprays also have UV absorbent chemicals. Here in the US there are actually sprays specifically formulated to absorb UV (used for preserving art) and that is what I have used here...