Transactions (1871) (14597359228)

Identifier: transactionsmining36amer (find matches)
Title: Transactions
Year: 1871 (1870s)
Authors: American Institute of Mining, Metallurgical, and Petroleum Engineers
Subjects: Mineral industries
Publisher: New York (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto



Text Appearing Before Image:
Fig. 8 (B).Photomicrographs of Thin Sections of Sulphide Ore from Austin villeMines, Wythe County. Magnified 50 Diameters ; Cross Nicols.Black areas represent sulphide minerals. Shows crystalline character oflimestone and its replacement by the sulphides. Re-entrant angles alongmargins of the sulphides and the spider-like arrangement of the sulphideareas, as a whole, are well shown. 698 LEAD- AND ZINC-DEPOSITS VIRGINIA-TENNESSEE REGION. 2. The Oxidized Ores.—Where sufficient developments havebeen made, as in the mines of Wythe county, Va., the oxidizedores usually show much richness, and they are often concen-trated in massive form as large irregular masses and layers.
Text Appearing After Image:
This is especially true of the calamine, which forms the domi-nant oxidized ore. So massive was the calamine in places inthe old Bertha mines, that blasting is reported to have beennecessary for its removal. LEAD- AND ZINC-DEPOSITS VIRGINIA-TENNESSEE REGION. 699 Concentration of the oxidized ores has taken place princi-pally at and near the bottom of the residual clays, closely hug-ffino: the irregular weathered surface of the limestone, as shownin Figs. 2 and 3. Frequently, several inches separate the mas-sive form of the ores, calamine and smithsonite, from the lime-stone. This space is tilled, oftentimes, with a loose powderyform of admixed calamine and smithsonite. At times, thepartly decayed limestone, in pulverulent granular form, partlyor entirely fills the space. Much galenite is intermingled inplaces with the concentrated calamine and smithsonite in thelower portion of the clays. Usually, when associated with theoxidized ores in the way mentioned, the galenite is observed tod