Transactions of the American Institute of Mining, Metallurgical and Petroleum Engineers Volume 23 (Paperback)

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. 1894 Excerpt: ...and fragments of the capd. When several fissures come together, the result is somewhat complicated, but can be reduced to the simple case just described. Seuet Jahrb.f. Mineralogie, 1876, p. 434. t "Remarks on Some Tin-Lodes in the St. Agnes District," Tram. Roy. Geol. Soc. of Cornwall, 1877, ix., PI. III. Still more interesting is the tin-deposit of East Wheal Lovell, described by the same authority. At the side of a narrow quartz vein the ores occur in the granite, from which they are not separated by any definite boundary, so that the ore-body is an almost vertical shoot, confined to the neighborhood of the fissure, yet lying in the country-rock. It is clear that a mineral water-of high solvent power, must have ascended under great pressure, in order to bring about such effects in a rock ordinarily regarded as insoluble. Fig. 93 shows the situation of one of these ore-shoots in granite, at the East Wheal Lovell mine. The ore-deposits in metamorphous and eruptive rocks occur especially in the great crystalline northern areas, in Scandinavia, Canada, and the northeastern United States. Scandinavia.--In Scandinavia, the science of ore-deposits, like that of petrography, has had a comparatively independent development. Although these countries have been often visited by foreign observers, few analogies with European deposits have been noted--chiefly, no doubt, because of the peculiar character of the occurrences examined, but also partly because of the differing standpoints and views of native observers. In recent times a difference of interpretation has developed itself between the Norwegian and the Swedish geologists; and the former, since Kjerulf, have approached more nearly the Continental view. As already remarked, Kjerulf traces all the ore-d...