Jean François de Lamoignon (shortened to Jean or John Lemoigne) was a black-bearded Frenchman who differed from most of the other early Death Valley prospectors; he was a well-educated mining engineer. He came to Death Valley around 1879 to supervise the Eagle Borax Works. Unfortunately, by the time he had arrived in Death Valley, his partner who brought him out there, Isidore Daunet, had committed suicide. Lemoigne turned to prospecting.
Lemoigne traveled far and wide around Death Valley country and discovered a few mines over the years, but up in the Cottonwood Mountains, he discovered a lead-silver ore body that was his favorite. He worked his mine only on a very small scale. He never developed it beyond what he needed to live off of at the time. He referred to it as his “bank.”
