MAGNETITE AND PYRITE. 123 



2.03.05. Example I2b. New York and New Jersey Highlands, 

 and the South Mountain of Pennsylvania. Beds of lenticular shape 

 in Archaean gneiss and crystalline limestone. From Putnam County, 

 New York, a ridge of Archaean rocks runs southwest across the 

 Hudson River, traversing Orange County, New York, and northern 

 New Jersey, and running out in Pennsylvania. Lenses of magne- 

 tite occur throughout its entire extent. They are not as large as 

 in the Adirondacks, but are more regularly distributed. East of 

 the Hudson, in Putnam County, the Tilly Foster mine is the most 

 important, and the descriptions and figures of it are the best illus- 

 trations of the shape of lenses published. West of the Hudson, in 

 Orange County, the Forest of Dean mine affords considerable ore 

 yearly. It is cut by an interesting trap dike. As the results of 

 study of the Archaean of this region, N. L. Britton has divided it 

 into a Lower Massive group, a Middle Iron Bearing, and an Upper 

 Schistose. (Geol of N. J., 1886, p. 77.) F. L. Nason has also 

 sought to classify it on the basis of rock types, of which he makes 

 four, named, from their typical occurrences, Mount Hope type, 

 Oxford type, Franklin type, and Montville type. They are ar- 



bine, " Crystalline Magnetite in the Port Henry (N Y. ) Mines," M. E., Feb- 

 ruary, 1890. Rec. H. Credner, Zeitsch. d. d. g. Gesell. , 1869, XXI., p. 516; 

 B. und H. Zeit., 1871, 369. J. D. Dana, "On the Theories of Origin," 

 Amer. Jour. Sci., in., XXII. 152, 402. E. Emmons, Geology of New York, 

 Second District, pp. 87, 98, 231, 255, 291, 309, 350. Hist. C. E. Hall, 

 "Laurentian Magnetite Ore Deposits of Northern New York," 32d Ann. 

 Rep. State Museum, 1884, p. 133. Rec. J. F. Kemp, " Notes on the Miner- 

 als Occurring near Port Henry, N. Y.," Amer. Jour. Sci., iii., XI. 62, and 

 Zeitsch. f. Kryst., XIX. 183. G. W. Maynard, "The Iron Ores of Lake 

 Champlain," Brit. Iron and Steel Inst., Vol. I , 1874. W. C. Redfield, 

 "Some Account of Two Visits to the Mountains of Essex County, N. Y., 

 in 1836-37," Amer. Jour. Sci., i., XXXIII. 301. Hist. B. Silliman, "Re- 

 marks on the Magnetites of Clifton, St. Lawrence County, N. Y.," M. E., 

 I. 364. J. C. Smock, "Iron Mines of New York," Bull. VII., N. Y. State 

 Museum. Rec. J. Stewart, "Laurentian Low Grade Phosphate Ores," 

 M. E., February, 1892. Wedding, Zeitschr. /. B., H., und S. im. p. St., 

 XXIV. 330, 1876. See also the general works on Iron Ores cited at begin- 

 ning of Part II. On Canadian magnetites the following papers may be 

 mentioned. F. P. Dewey, "Some Canadian Iron Ores," M. E., XII. 192. 

 B. J. Harrington, " On the Iron Ores of Canada," Can. Geol. Survey, 1873- 

 74. T. S. Hunt, Can. Geol. Survey, 1866-69, pp. 261, 262. T. D. Ledyard, 

 " Some Ontario Magnetites," M. E., XIX. 28, and July, 1891. W. H. Mer- 

 ritt, " Occurrence of Magnetite Ore Deposits in Victoria County, Ontario," 

 A. A. A. S. t XXXI. 413, 1882. 



