From the Guidebook:
Centered about the "Town of Calico", the Calico Mining District,
with a peak population of 3,000, produced
$13-20 million in silver and $9 million in borate
minerals between 1881-1907. On April 6, 1881, several
claims were located which formed the largest
mine in the district, the Silver King. Profitable mining of silver ceased in 1896.
Plaque placed by the State Department of Parks and Recreation in cooperation with San Bernardino County, Regional Parks Department. May 12, 1973