I have never seen this hallmark before - It is on the back of a round, 3" diameter, hand-tooled Thunderbird pendant made from nickel silver - Any help with this would be greatly appreciated; thanks for your time and expertise.
Thank you very much; you saved me the humiliation of listing this piece online as Native American (probably not the first time you've set a greenhorn straight!) I'm glad I joined this forum to do this and other research, thanks again -R