Statistics and Observations on the Mines of Cornwall and Devon ...

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Darling and son, Printers, 1860
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Page 39 - Deposits of this nature are less common than the two former classes ; they usually contain either copper or lead, and some of the rich oxides of iron appear to belong to a similar formation. Fragmentary Deposits occur associated with and indeed forming part of many of the loose superficial beds of sand and gravel which occur...
Page 28 - In the year 1808, it was declared by Captain James Michel, one of the best Cornish miners of that day, to be "not worth a pipe of tobacco !" In 1809, Mr. Joshua Rowe of Torpoint, and co-adventurers, notwithstanding the general contempt for the mine, commenced working it again. As it still remained poor, the adventurers dropped off one by one, leaving the entire cost of working upon Mr.
Page 39 - The mineral substances found in these deposits, which may be considered as having originally been derived from veins or beds in the vicinity, are not, in most cases, mixed up indiscriminately with the alluvial matter, their greater specific gravity having occasioned them to be deposited in distinct layers by themselves, usually towards the bottom of the mass.
Page 27 - ... hollow. You see the whole at once, and in these particulars you will not find any other mine like it. No shafts of any depth are sunk below its base ; and it would seem as if a complete mine had been turned inside out, for the benefit of timid...
Page 42 - ... and more or less mixed with metals and their ores. They have commonly one prevailing direction, subject to slight irregularities and curvatures, as well in length as in depth. They traverse granite, slate, and the elvan«, indiscriminately, and almost always without other, interruptions than what may take place from their interference with each other and with the foreign mterruptions, locally called cross-courses, flucans, and slides.
Page 39 - ... oxides of iron appear to belong to a similar formation. Fragmentary Deposits occur associated with and indeed forming part of many of the loose superficial beds of sand and gravel which occur in the valleys of mineral districts, consisting of the detritus of the neighbouring mountains, •which has been washed down from thence at remote geological epochs. The mineral substances found in these deposits, which may be considered as having originally been derived from veins or beds in the vicinity,...
Page 40 - Any one may satisfy himself of this fact by inspecting in our museums, specimens of certain tin and copper ores in the rough. The most important of the mineralizing substances are oxygen and sulphur. The next in rank are chlorine, and the sulphuric, carbonic, and phosphoric acids. The mode in which they combine with the metals is, chemically speaking, either in binary compounds, or in the union of two pairs of such compounds. Of the former we have examples in iron, lead, and mercury, which, when...
Page 45 - Carne states that they occurred at the depth of tiOO ft. below the surface in the tin lode, the mass being about 12 ft. in length, and as many in width and thickness, scattered pebbles being found in the vein far beyond the boundaries. It has been doubted that these are true pebbles ; those specimens, however, which the survey procured from various sources, some from Mr. Carne himself, can leave little doubt on the subject, more especially as rounded pebbles of quartz are mixed up with...
Page 37 - ... dislocations. St. Michael's Mount is as interesting geologically as historically, and it is the solitary prominence of granite in that district. That part of its base which lies towards Marazion is of slate, •whilst its summit and southern side are of granite. The junction of the two rocks is well shown on the beach, where also are seen the granite veins by which the slate is traversed. They may be readily reached and observed at low tide, and are seen to proceed from the main mass of the granite,...
Page 38 - ... older veins. Apart from considerations of age, there are other circumstances, dependent apparently upon local influence in the distribution of metals, which aie also worthy of notice. The slates, for instance, of Cornwall and Devonshire are of nearly the same geological age as those of North Wales and Cumberland ; but the metalliferous ores found in them differ exceedingly — tin abounding chiefly in the southern counties, copper being the staple in the central and some parts of the northern,...

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