The Quarterly journal of the Geological Society of London . s east of the Cliff, is opened upona similar lode, consisting of a series of alternations of red laumonitestrings, with large lenticular expansions containing copper. Theoriginal discovery of this lode was made in an old Indian working atthe No. 2 shaft, out of which a mass of copper, weighing 50 tons,was taken. Only a small amount of metal has been found imme-diately below this point in sinking; but further north, below thegreenstone, under similar conditions to those observed in the Cliffmine, a very rich run of ground has been disc
The Quarterly journal of the Geological Society of London . s east of the Cliff, is opened upona similar lode, consisting of a series of alternations of red laumonitestrings, with large lenticular expansions containing copper. Theoriginal discovery of this lode was made in an old Indian working atthe No. 2 shaft, out of which a mass of copper, weighing 50 tons,was taken. Only a small amount of metal has been found imme-diately below this point in sinking; but further north, below thegreenstone, under similar conditions to those observed in the Cliffmine, a very rich run of ground has been discovered. There is agood deal of calcspar in the vein, and the finer copper appears ratherin sheets than in shots. At the 50-fathom level, on the No. 4 shaft,the largest mass that has as yet been discovered on the lake wasstruck; it measured 50 feet in length, 30 in height, and about 4|feet in greatest thickness, and yielded somewhat over 500 tons ofcopper. Pig. 5.—Longitudinal Section of the Central Mine, No. 1 Shaft. No. 2 Shaft. N. 15° W. No. 4 The mines in the range north of the greenstone are the Petherick,Copper PaUs, and Phoenix, which derive their produce almost entirelyfrom a remarkable bed of very much decomposed finely vesiculartrap, filled with small shots of copper, known locally as the ash-bed. Associated with this is a compact trap, containing elongatedcavities at its contact with the more vesicular portions. Thesecavities are usually filled with copper in ramifying forms resemblingeagles claws. The ash-bed, according to its discoverer, Mr. Hill,has been traced for about 8 miles, and by its position probablyrepresents some of the upper beds of Portage Lake. Although ex-tensively worked, it is too poor to yield any great profit, the produceat Copper Palls being 1 per cent., and at the Phoenix only | percent., of the rock treated. 2i2 458 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 11, 7. Ontonagon District.—The mines of this district are all opened int
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectgeology, bookyear1845
