Transactions . ck has been incorrectly describedas syenite by F. P. Gamba {Riqueza Mineral de la Republica de Colombia, p. 62(1901). H. W. Nichols and O. C. Farrington state it to be an andesite or a tra-chyte, but the specimens examined were too much altered by the action of thevein-liquors for exact determination. The Ores of Colombia, Field ColumbianMuseum, Publication No. 33, Geological Series, vol. i., No. 3, pp. 132, 133. PEBBLES AND CONCRETIONS IN METALLIFEROUS VEINS. 161 The galena, as a rule, is highly auriferous, pyrite much lessso; the remaining pyritic minerals usually bear a certa
Transactions . ck has been incorrectly describedas syenite by F. P. Gamba {Riqueza Mineral de la Republica de Colombia, p. 62(1901). H. W. Nichols and O. C. Farrington state it to be an andesite or a tra-chyte, but the specimens examined were too much altered by the action of thevein-liquors for exact determination. The Ores of Colombia, Field ColumbianMuseum, Publication No. 33, Geological Series, vol. i., No. 3, pp. 132, 133. PEBBLES AND CONCRETIONS IN METALLIFEROUS VEINS. 161 The galena, as a rule, is highly auriferous, pyrite much lessso; the remaining pyritic minerals usually bear a certain pro_portion of gold, with the exception, perhaps, of pyrrhotite,which appears to occur only where the vein is poor. Some free gold occurs in the vein, even below bullion from the rich shoot, below water-level, averages afineness of 609 gold and 358 silver. The structure of the vein is a roughly-banded one; beinggenerally composed of several layers of quartz and pyrites par-allel to the A, Hornblende-granite ; B, Solid quartz with patches of pyrite ; C, Solid quartzwith lines of pyrite, sphalerite and galena ; D, Oxidized ore with crumbly quartz. Fig. 1.—Cross-Section 2 Ft. Above the Fourth Level. Fig. 1 is a sketch of the vein, showing the general structure,taken a few feet above the fourth or day -level. Next thehanging-wall is a layer of solid quartz, containing patches ofpyrite. The center is formed of a band of solid quartz, withlines of pyrite, sphalerite and galena, distributed as shown;between these layers the quartz contains patches of pyrite the foot-wall is a layer of oxidized ore in crumbly quartz. The Spaniards use the term Jilon (Fr. Jilon) for veins or lodesof large size, smaller ones being termed veta, vena, and thediminutives, vetica, veticilla, vetilla, venilla. In Mexico, and inSpanish-America generally, veta is used to designate a vein or 162 PEBBLES AND CONCRETIONS IN METALLIFEROUS VEINS, lode,^on being sometimes applie
Size: 1761px × 1418px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
