Bulletin, Issue 15, Part 1

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Virginia Geological Survey, 1918 - Geology
 

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Page 18 - The metallic coating has a dull gray, somewhat leaden appearance, but it may be made lustrous by rubbing with a soft cloth or with the hand. If the hand is used, the characteristic odor given off when tin is rubbed on the flesh may be noted.
Page 1 - THE United States is almost entirely dependent on foreign countries for its supply of tin. As this metal is a war-time necessity, and as a domestic source of supply is urgently needed, all known deposits of tin ore (cassiterite) in the United States have recently been examined by geologists of the United States Geological Survey, Department of the Interior. One of the most promising of these deposits is in the Irish Creek district, in the eastern part of Rockbridge County, Va., near the summit of...
Page 5 - Cassiterite is the tin-bearing mineral of the deposits. It is found in quartz veins that cut the hypersthene granodiorite and in the adjacent altered granodiorite. In addition to quartz and cassiterite the deposits contain arsenopyrite, pyrite, siderite, wolframite, scheelite, muscovite, fluorite, and beryl. Most of the cassiterite shows crystal faces, though no perfect crystals were seen.
Page 18 - The simplest and easiest test for cassiterite is to place a fragment of the mineral in dilute hydrochloric or sulphuric acid with granulated, shot, or sheet zinc. The zinc and the acid rapidly evolve hydrogen, which takes the oxygen from the mineral and leaves a coating of tin on the fragment tested. Granulated zinc is the best to use, as its small particles can be made to touch the specimens at many points and thus bring more of the hydrogen in contact with the molecules of tin-oxide. The reaction...
Page 3 - Since that time no systematic attempt has been made to work the deposit. It is said that a small amount of tin has been smelted in blacksmith forges near the deposit. The long period of idleness from 1893 to the present time appears to be due to uncertainty as to title to the property rather than to lack of confidence in the value of the deposits. GEOLOGY. The rocks of the district are mainly granodiorite, granite, and granitic gneisses, all probably of pre-Cambrian age, Cambrian sedimentary rocks,...
Page 7 - Colorado ferberite and the wolframite series: US Geol. Survey Bull. 583, p.
Page 2 - Va., in 184G,S and it is reported that some prospecting was done in the region during the next few years, but afterward the existence of the ore seems to have been forgotten. The ore was rediscovered in 1882 by Mrs. Martha D. .Cash, prospecting began in 1883, and the Virginia Tin Mining and Manufacturing Company was organized in 1884. By this time a tunnel 80 feet long had been driven on the vein.0 The Lexington Tin Company appears to have operated in the • Washington and Lee University.
Page 11 - ... and beryl, rather than of muscovite and fluorite as in the other veins. No cassiterite was seen in the specimens from this vein. A large pile of waste rock, about 75 feet south of the developed vein, is said to have been placed there to conceal the outcrop of a small vein that is excedingly rich in cassiterite.
Page 11 - ... district is said to have confined its attention to the No. 1 workings, and probably most of the tin produced came from this vein. About 100 feet north of the No. 1 workings a small open cut exposes a 3-inch quartz vein carrying a considerable amount of beryl in long, slender crystals and some muscovite in small plates. The granodiorite next to the vein is greatly altered, but the alteration here consists of replacement of the original rock by an aggregate of muscovite and beryl, rather than of...

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