File:Transactions (1871) (14597388357).jpg

Identifier: transactionsmining36amer (find matches)
Title: Transactions
Year: 1871 (1870s)
Authors: American Institute of Mining, Metallurgical, and Petroleum Engineers
Subjects: Mineral industries
Publisher: New York (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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untain is this very persistence in depth, proven in the Yan-kee Girl, Congress, Genesee-Yanderbilt, Silver Bell, and Gustonmines, to the depths attained. I do not recall a single instanceof a chimney on the above-named properties where the terms lenticular or spindle-shaped would apply as descriptiveof the form of the ore-bodies. Their formation by replacementof the breccia is well proved; and the merging of the ore, whichoccurs massive and quite free from silica or waste, into thecountry-rock on nearly all sides is characteristic. It is truethey were sometimes very erratic and difficult to follow, espe- 2 The Ore-Deposits of Red Mountain, Ouray County, Colo., Trans., xviii., 139-145 (1889-90). Also xxvi., 1056-1059 (1896). 3 Op. tit., p. 107. OCCURRENCE OF ORE AT RED MOUNTAIN, COLORADO. 33 cially in the upper levels, owing to the absence of any definedslip or fracture leading to the ore-body, or connecting two ormore chimneys. In opening a new level, the ore-break, or belt of altered
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YANKEE GIRL MINE PLAN Showing Ore-Break at theSecond Level, and portions ofcontalning-walls, as determinedby development in the lowerlevels. East Wall ^<^-<rWest Wall -^tcuiin. Fig. 1.—Plan of Yankee Girl Mine, Showing also the Position of Centers of Chimneys. breccia in which the chimneys occurred,4 was first located.In this area there might be some one fracture-plane, perhapsvery obscure, which if followed would lead to a chimney; but * Trans., xxvi., 1056-1059 (1896). 34 OCCURRENCE OF ORE AT RED MOUNTAIN, COLORADO. as such planes rarely had the same course on two successivelevels, the finding of the quartz or siliceous envelope of theshoot was, in the upper portions of the ore-bodies, the firstnotice of their proximity. The difficulty of following the pay was increased by the utter uncertainty of the positionof the areas of massive andesite. (See Fig. 1.) These well-defined masses enclosed no ore-bodies, and were very modula-tory, both vertically and horizontally. Whether a

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