ZINC ALONE. 119 



yet such abundance of zinc is beyond previous experience. It is, 

 however, suggestive that no inconsiderable amount of zinc is found 

 in the Low Moor (Va.) limonites, as shown by the flue dust (see 

 E. C. Means, " The Dust of the Furnaces at Low Moor, Va.," Buf- 

 falo meeting Amer. Inst. Min. Eng., October, 1888), and this 

 in the* course of a protracted blast may amount to many tons, 

 but it does not approach the Franklin Furnace ores. None the 

 less, in the absence of a better explanation, the franklinite bed 

 may be thought of as perhaps an original manganese, zinc, iron de- 

 posit in limestone, much as many Siluro-Cambrian limonite beds 

 are seen to-day, and that in the general metamorphism of the re- 

 gion it became changed to its present condition. Minerals of the 

 spinel group occur all through this limestone belt, and in Orange 

 County, New York, to the north, there is an old and prolific source 

 of them. 



2.07.09. If it is possible to demonstrate the connection between 

 the white limestone and a granite dike, as Mr. Nason argues, this 

 may have been an important factor in the ore formation. It is 

 very reasonable that the igneous intrusion should start ore-bearing 

 currents along a certain stratum in the limestone, which would re- 

 place it with ore. Subsequent folding and metamorphism must 

 then have changed these ores, whatever they were, to the present 

 unusual minerals. 1 



2.07.10. Blende is known in numerous places in the Rocky 

 Mountains and is often argentiferous, but it is not as yet profit- 

 ably smelted for zinc, and is a drawback to the lead-silver pro- 

 cess. 



2.07.11. A large amount of zinc ore is turned directly into zinc 

 white and employed as a pigment. For this reason later statistics 

 of the metal do not indicate all the ore mined. The accompany- 

 ing figures are short tons. For detailed statistics see the volume on 

 " Mineral Industry " of the Engineering and Mining Journal, 

 1893. 



1 F. Alger, " On the Zinc Mines of Franklin, Sussex County, N. J.," 

 Amer. Jour. Sci., i., XL VIII. 252. Bemis and Woolson, An unpublished 

 thesis in the School of Mines Records, 1885. H. Credner, " On the Frank- 

 linite Beds," B. und H. Zeit., 1866, 29, and 1871, 369. Geol. of New Jersey, 

 1868 (with a map), and subsequent Annual Reports. F. L. Nason, Ann. 

 Rep. State Geol. N. J., 1890, p. 25. Rec. Amer. Geol., VIII. 166. Van- 

 uxem and Keating, " On the Geology and Mineralogy of Franklin, Sussex 

 Oounty, N. J.," Phil. Aead. Sci., Vol. II., p. 277. 



