Hi Red_ desert,
What a beautiful artifact! I believe your vial is of a date range from 1760-1850, and not of Hispanic origin. It was likely pharmaceutical, holding a medicine. Vials like those were carried by the fur traders and explorers who conquered the North American frontier. The military also had them as part of their official supplies. Many were given to Indian leaders as gifts for better relationships and to entice them to bring in better furs. Based on archaeological reports, is not uncommon to discover these containers within Indian burials and Native camps. Perhaps the area you speak of was once an occupied mission spot and then developed into a post with other purposes. I have researched the French occupation up through the Midwest quite thoroughly, but mostly that history of an earlier period, directly related to my 1715 Fleet study and writing. PM me, though, if you are interested in some of my references which should help give a better understanding to this intriguing find.
Laura J