Regular Meeting, April 15th, 1867.
Vice President Ransom in the Chair.
Thirty-three members present.
The collections made during the field meeting on Angel Island were exhibited and commented on.
Professor Silliman read the following paper:
Notice of a peculiar mode of the occurrence of Gold and Silver in the Foot-Hills of the Sierra Nevada, and especially at Whisky Hill, in Placer County, and Quail Hill, in Calaveras County, California.
BY B. SILLIMAN.
In the search for ores of copper which occurred in California in what is now known as the “Copper Belt” of the Lower Sierras, deposits of “Iron Rust,” as they were called by the miners, were observed at numerous points far below the range of the main gold belt of the Sierras. Several of these ochraceous deposits had been previously “located” by prospecting miners for gold, before there was any knowledge, or suspicion even, of the existence of ores of copper in connection with them. It was a matter of common observation that certain gulches, or watercourses in the neighborhood of these rusty deposits, were rich in placer gold, having been worked for gold from an early date. The search for copper in this kind of deposit was not commercially successful, although there were shipments of green and blue carbonates of copper, red oxide and metallic copper, to a limited extent from both the localities here referred to, the metal from which was known to contain a notable value of gold and silver, stated to be about fifty dollars to the ton of ore. This search for copper has, however, opened up these deposits so as to display their character in a conspicuous manner.