The following notes concerning the metal prospects of the Los Burros district, in the southwestern part of Monterey County, California, are based on observations made during a visit of a few days to this section of the Santa Lucia Range in February, 1921.

The Spenceville Copper Mine, located in Spenceville, Nevada Co., California, operated between 1863 and 1918. In its day, it was considered one of the most long-lived copper mines in the state.

Horace Austin Warner Tabor (November 26, 1830 - April 10, 1899), also known as Silver Dollar Tabor and The Bonanza King of Leadville, was an American prospector, businessman, and politician born in Holland, Vermont to Cornelius Dunham Tabor and Sarah Ferrin.

The Colorado Gold Rush was the boom in the prospecting and mining of gold in present-day Colorado in the United States that began in 1859 (when the land was still in the Kansas Territory) and lasted throughout the early 1860s.

The Colorado Silver Boom was a dramatic expansionist period of silver mining activity in the U.S. state of Colorado in the late 19th century.

The sources of data for the silver worksheet are the mineral statistics publications of the U.S. Bureau of Mines and the U.S. Geological Survey Minerals Yearbook (MYB) and its predecessor, Mineral Resources of the United States (MR); and Mineral Commodity Summaries (MCS) and its predecessor, Commodity Data Summaries (CDS).