REVIEWS 479 



manganese iron, especially well adapted for car-wheels, has long been 

 prepared by the old charcoal process. Iron has been mined almost con- 

 tinuously since 1 734. Most of the mines are located at or near the boundary 

 of the areas of Hudson schist with those of the Stockbridge dolomite, both 

 of which are Cambro-Ordovician sedimentaries. The more important of 

 the exploited ore beds form a nearly continuous series encircling the base 

 of Mt. Washington. The author believes that the ore was derived from 

 pyrite in the Berkshire schists of the adjacent elevated territory, and that 

 the ore bodies have been formed by the replacement of Berkshire schist 

 and Stockbridge dolomite. 



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Lead and Zinc Deposits of Virginia. By Thomas Leonard Watson. 

 (Geological Survey of Virginia, Geological Series, Bulletin No. i. 

 Pp. 156, 14 plates. Published by the Board of Agriculture and 

 Immigration, Richmond, Va., 1905.) 



Galenite and sphalerite are associated in all the mining districts, gener- 

 ally as replacement deposits in limestone breccia near faults, and on anticlinal 

 axes. The sulphide ores show no secondary enrichment. The most inter- 

 esting feature of this region is the secondary oxidized ore which occurs in 

 depressions of the weathered surface of the limestone beneath several feet 

 of residual clay. This ore consists of predominant calamine, associated 

 with smithsonite, and cerrusite, and toward the bottom there is generally 

 some galenite. Commercial ores are limited to the Shenandoah Limestone. 



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The Paragenesis 0} the Minerals in the Glaucophane- Bearing Rocks 

 of California. By James Perrin Smith. (Proceedings of the 

 American Philosophical Society, Vol. XLV, 1906, pp. 183-242.) 



This paper, and the one by H. S. Washington published last year, make 

 a nearly complete study of the glaucophane schists and related rocks. Pro- 

 fessor Smith shows that the glaucophane rocks of the Coast Ranges have 

 been derived from siliceous fragmental sediments, deposits of organic silica, 

 acid arkoses, medium-basic clay shales, basic tuffs, syenites, diorites, dia- 

 bases, gabbros, and probably pyroxenites. The origin may be determined 

 by study of the chemical composition. Metamorphism has consisted 

 merely in recrystallization, no material has been added or taken away, 

 except that the water which once existed in the pore spaces has been included 

 as water of crystallization. The paper includes thirty-two chemical analyses, 

 and petrographic descriptions of the minerals and rocks. 



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