Geology of the Little Belt mountains, Montana; with notes on the mineral deposits of the Neihart, Barker, Yogo, and other districts - Softcover

Weed, Walter Harvey

Softcover

ISBN 10: 1231179597 ISBN 13: 9781231179598

Verlag: RareBooksClub.com, 2012

Über diesen Titel

Reseña del editor:

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900 Excerpt: ...all show silver sulphides deposited by secondary enrichment as crusts or crystals lining cavities, or as films or thin coatings along fractures of the primary ore, or in the oxidized zone as the so-called "sooty sulphide" ores that occur with manganese oxides. It is from this zone of enrichment that the high-grade ores, running from 200 to 1,000 ounces of silver to the ton, or even higher, were obtained in the early history of the camp. Although such ores played out in depth and caused many disappointments and failures, their occurrence played a most beneficial part in causing the development of the veins. While the secondary enrichment of copper veins along a level between an upper zone of oxidation and the unaltered vein material below is a well-recognized fact, a similar enrichment of silver veins appears to have escaped general recognition. The secondary minerals recognized are chiefly polybaaite and ruby silver, the former being more abundant. There are also bright metallic coatings, presumably argentite, ou crystals and along fracture planes, and rarely in minutely crystalline masses. The chemical changes by which the primary sulphides split up and yield these minerals have not been investigated. The change is presumably the result of superficial alteration in which the primary vein minerals are broken up (chemically) and their silver contents are partially leached out and carried downward and deposited in the upper parts of the sulphide zone. Briefly stated, the process is believed to be a partial leaching out of the silver contents from the outcrop of the vein by surface waters and the precipitation of the silver at somewhat lower levels. The superficial alteration of the Neihart veins is not a marked one, as there are no great zones of ca...

Über diese Auflage

• Verlag: RareBooksClub.com
• Erscheinungsdatum: 2012
• ISBN 10: 1231179597
• ISBN 13: 9781231179598
• Einband: Tapa blanda
• Anzahl der Seiten: 148