[Mark]

Well, you are comparing the patina on two different metals. Copper tends to stabilize more quickly than iron. The copper behind the pommel would not have been subject to as much contact as the handle and blade, so wouldn't the patina there naturally become deeper? The handle and blade were probably regularly cleaned and worn with use, even, preventing the building up of a patina at all until the item went from working tool to historical artifact. There are also a few explanations for the presence of such "new-looking" rust on the rivets, such as again the fact that rust might have been kept off while it was in actual use, then took hold after it was collected put in a drawer somewhere (they might even be replacements for old ones that rusted away).

I'm just saying that we shouldn't reach any firm conclusions based on the rust on the rivets and differences in the copper patina.

Somthing Jose wrote a while back surprised me and I meant to comment on it. Mother-of-pearl was not available in the Pacific NW until the turn of the century? I would have thought that bits of mussel shells would have been a staple embellishment for a long time, and even abolone is found along the California coast somewhere (good trade item, there). Shell decoration was pretty common among other No. Am. tribes, I believe even pre-Columbian. An intriguing anthropological quirk.