Someone asked our department for "help to identify the substance that some artifacts are made of. We have two artifacts that are made from an unknown substance and are reacting with either the air, or the glass, and leaving odd stains on the glass in the exhibits."

We asked for more information and the person said . "I think they are from the Late Roman Period but their authenticity I question. However, it's just a gut feeling and I have nothing that proves they are not authentic. They were found in the land of Israel but we are not sure where as they were purchased in a store."

Would anyone have a suggestion about this?

Thanks,
Nancy
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