In the early days of lode gold mining, stamp mills were used for crushing the ore. Where there was free gold in the ore, a silver-plated copper plate was placed so that the discharge through the screen from the mortar, with the addition of water, flowed down over this plate which was coated with quicksilver, allowing the free gold to become amalgamated and retained on the plate. The man who operated such a mill was called an amalgamator.
As the title suggests, the subject matter in this book deals for the most part with the examination and testing of placers. It is intended primarily as a guide for the professional mineral examiner who examines mining claims located on public lands of the United States.
When the Berkley mine broke out afire the other day in Butte, Montana, sending five hundred men to the surface and suspending operations for a month in one of the biggest producers of the greatest mining camp on earth -- the camp that gives to the world's market one-fourth of its copper production -- the sight of the flames and smoke didn't cause as much as a ripple of excitement on the surface of the busy population at the foot of the hill, for Butte is accustomed to a mine fire that is perpetual and which burns with intense heat in the ground under her very business district.
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.
Among the comparative tests the most remarkable was that in Cornwall, England, where the Ingersoll drill worked in competition with the diamond drill, when the former bored the same depth of hole in half the time it could be accomplished by the diamond drill.
The substitution of a mechanical power in place of the hand-labor formerly exclusively used for drilling rock, has been a subject of much thought, and many attempts have been made, with greater or less success, until the rock drill by improved machinery became of late years a firmly established institution, and the credit of this belongs, to a great extent, to the improvements made by Mr. Ingersoll, as he overcame the defects connected with former attempts, which were excessive weight, imperfect action, easy derangement, frequent damage, and costly repair.
This article was originally published in Manufacturer and Builder Magazine March of 1870. Excerpt: WHEN, a few years ago, the writer of this article found in the French journals an account of a new application of the diamond, namely, for boring rocks, and gave to an American newspaper a translation of it, which went the rounds of the whole press of the United States, the story was disbelieved by many, and was thought absurd and extravagant. It was indeed known that glaziers use diamonds to cut glass, and that engravers on glass and precious stones employ them; but to use diamonds to bore in common rock, instead of the usual large steel punches and drills, was supposed by some to be the height of foolishness.
California has been the source of more than 106 million troy ounces of gold, the most productive state in the Union. This digitized publication by the California Division of Mines & Geology contains information on approximately 350 gold mining districts.
This is part two of a series of articles from the Book "Principal Gold-Producing Districts of the United States" published by the USGS.
While this is not exactly mining history, I thought that this event was an important enough event in the general history of the West that it deserved a section on this site. San Francisco was the center of finance and industry for many of the western mining frontiers, so this section is actually appropriate to the theme of this site.