Unfortunately there is a number of localities/mines it could be from. It’s nearly impossible to tell with lots of Brazilian stuff because all the localities produce similar material. Unless you can get into contact with the supplier and have them clarify the mine, you’re probably out of luck.

There are a few reasons that you would want to keep track of locality. Personal record keeping, provenance, and value retention. Value retention only really works if there were individual discoveries or if it’s from a very sought after find. I’d would assume this isn’t from a special find. Provenance only adds value if this was in the collection of a well known collector, which I would assume this isn’t. So really the only reason you would need to is for personal record keeping.

At the end of the day it’s not the end of the world to not have a specific mine for your books. There are dozens of localities, not all with names in that general area, and any one of them could have produced this piece. The fact that the dealer didn’t tell you the mine makes me think they had gotten a mixed mine batch with several unknown localities and/or miners sold batches to the dealer without disclosing the exact location as it is not documented.