With respect to chemical analysis, the word "spark" gives me the shivers.
There is a process, known as X-ray fluorescent analysis which may be applied with absolutely no marking of the metal. I am retired Director of Technology from a specialty metal supplier, Rolled Alloys. They have a wonderful device in the lab, at least the one I used was called: Innov-X Systems Model #XT-245S spectrometer. I was able to test the brass/bronze on a number of 19th century firearms, and the odd old coin with this device. Somewhere at the U of Az someone must have a similar machine.
If you do not already know this, NEVER leave your artifact with a lab technician to analyze.
You must have your personal body present at all times. Otherwise he may well cut it up or melt it to give you an even Better analyses. Learnt this at first job, Black & Decker. A salesman for B&D collected Civil War items, and came in with a short artillery sword, might even have been Confederate. Wanted us metallurgists to take a look at it. My boss had a wonderful sense of humor, he planned to cut the blade in half, then mount & polish as specimen for metallography. We were able to talk him out of this approach, therefore avoiding potential homicide.
Lab guys have absolutely NO sense of humor, nor can they appreciate ancient things. This can hold true for archaeology students as well, in my experience. Well, I did see only one such student cheerfully chopping up early bronze age axes for metallographic examination. She told me they had plenty of them.
Anyway, X-ray fluoroscopy is the way to go, just make sure you are present. Lest they polish or grind some area to get a Better reading.
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