Does the dust/rock dissolve at all in white vinegar?
What did the
LFS have the rock labeled as? Can you get them to give you the supplier's name?
Can a strong magnet (old hard drive magnet, rare earth magnet, etc...) on a string pick up any of the dust? Will it "pull" towards any areas on the rock?
Bottom line: I'd quarantine for at least 8 weeks. Don't dose anything, not even buffer, just do big water changes every week or so and test the water regularly (including testing for
copper and iron).
