Tea Cup from Circa 1880's Mining Camp Dump, Southern Idaho

My late half-brother found this beautiful cup (not a crack or chip on it!) during a dig in an old mining camp dump (would have been pre-1990). Unfortunately, his mother does not remember the name or location of the old camp, but camps he frequented in their area (southern Idaho) dated in the 1880's.

I particularly love the design of the handle, with the little "band" that appears to wrap the bottom.

Measurements:
3-1/2" Cup Opening
1-3/4" Base Width
2-1/8" Height
4.2 oz Weight

Any help in identifying this enduring piece of history is appreciated!