What I should have written is that as far as I am aware Minas Gerais does not have the Amethyst geode bearing basalt like the basalt flows that extend throughout Rio Grande do Sul into Uruguay. Yes, it does have basalt flows as it is a known producer of zeolites and associated species but very few of these specimens have made it into international market. It is most unlikely that a Uruguayan amethyst specimen would be labelled as coming from Brazil so I am trusting that all the Amethyst /agate lined geodes with calcite are actually from Brazilian localities which would then put them as more than likely coming from Rio Grande do Sul as there is definitely no locality known in Minas Gerais that has ever produced these type of specimens.