From research, over ten years ago, I remember 1/8th being the minimum mix to qualify for status. Also for Native American status you needed to be tribally affiliated which required affiliation by your 18th birthday with tribal participation requirements. It all seemed so silly that I am part Cherokee but would have had to prove it when all other minority groups could just mark the block. I never used it because I couldn't adequately document my history and was way to old to tribally affiliate.