Dear pkrlvr17,
I know a little about these; I have seven of them, and missing only two, you have one of them.
I have the following:
1998 Geronimo
1999 Chief Joseph
1999 Sitting Bull
1999 Tecumseph
2000 Blackhawk
2000 Red Cloud
2000 Pontiac

There was also a coin dated 2001, it has a picture of Indian woman and child and is gold plated.
It is the same size as the one you have, and gold plated like a $20 or $40 silver strike.
I believe they were minted by Northwest Territorial Mint, PO Box 2148, Auburn, Wa. 98071-2148
(800)344-6468.

LMK if you are looking to sell.
Thanks,
Jay