The North Star Mining Museum is located in Grass Valley California. I found it when attending an engine show there this year. The items in the museum demonstrate that once upon a time the 'merikans were masters of their domain. There are some interesting engineering achievements located there which I have not seen anywhere else in the world ranging from a simple but amazingly effective variation on the simple water wheel (the Pelton Wheel) to a rotary stamp battery. I found the museum to be very interesting and my kids especially liked the curator who is eager to explain everything to the munchkins and very knowledgeable about the mining and the local area. He has made some of the models in the museum which demonstrate the various concepts. Well worth a visit. Admission is by dontation (suggested $2 per person at the door).