Bulletin - United States Geological Survey (Volume 293)

This historic book may have numerous typos, missing text, images, or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1906. Not illustrated. Excerpt: ... GOLD DEPOSITS. One great cause of the lack of success which has attended gold mining in this region lies in the fact that instead of one recognized and well-defined type of gold deposit, as is the case in most mining districts, there are various types exhihiting a very wide range in character, and individual mines present more and greater differences than similarities. Such conditions, whether they are appreciated or not, mean expensive mining. Advantage can not be taken of past experience to reduce the cost of exploitation. If methods which have proved successful in one mine are employed in another the chance is that they will be unsuccessful because they are not adapted to the dissimilar conditions of the second mine. Accordingly the owner is loath to apply to a new mine methods which have proved successful elsewhere, and is inclined instead to try new methods which may miss the mark as widely as those already in use. Because of this absence of a single type of deposit the study of this gold region has been not wholly satisfactory. In most mining districts the geologist sees more and more clearly into the character of the deposits as a whole as his work progresses, nearly every mine adding evidence to aid in the explanation of the type of deposit. In this region, however, the student of the ore deposits is confronted on all sides by new and perplexing features, which, instead of uniting to explain the main problem of the region, result simply in a mass of uncorrected and distracting facts. Especial and unusual attention has therefore been given to the mine descriptions, since nearly every mine possesses distinctive features and has an importance of its own. OCCURRENCE AND STRUCTURE. In spite of the apparently general dissimilarity in character of the ...