158 KEMP'S ORE DEPOSITS. 



except as having furnished beautiful crystals of oxidized lead 

 minerals. 1 



2.05.08. Example 22b. Sullivan and Ulster Counties, New 

 York. Veins along a line of displacement on the contact between 

 the Hudson River slates and the sandstones of the Medina stage 

 (Shawangunk grit), carrying galena and chalcopyrite in a quartz 

 gangue ; or else gash veins filled with the same in the grit. These 

 mines formerly produced considerable lead and copper, but are 

 now best known for the excellent quartz crystals which they have 

 furnished to all the mineralogical collections of this and other 

 lands. 2 



2.05.09. Example 23. Southeast Missouri. Galena accom 

 panied by nickeliferous pyrite, disseminated through beds of the 

 Third or Lower Magnesian limestone of the Missouri geologists, 

 which is doubtless Cambrian in age. The mines are at Bonne 

 Terre, Mine La Motte, and Doe Run, twenty-five miles west of the 

 Mississippi River and forty to one hundred miles south of St. Louis. 

 The strata lie almost horizontal, and are known to carry lead 

 through over 200 feet in thickness. The productive places fade 

 out into barren rock and appear to be local enrichments of the 

 limestone, of which the galena forms an integral part. At Bonne 

 Terre they are of enormous size, one working running 3000 feet, and 

 being 100 to 200 feet broad and 25 to 60 feet high. No zinc, how- 

 ever, occurs with the lead, and the silver contents are very small, 

 being about four ounces to the ton of lead. At Mine La Motte 

 some copper is found, and considerable nickel and cobalt. The 

 rare mineral siegenite, a variety of linnaeite, impregnates a sand- 

 stone supposed to be the equivalent of the Potsdam. Pyrite accom- 

 panies the galena both at Mine La Motte and at the other mines, and 

 carries the nickel and cobalt, which is obtained as a by-product in the 

 lead smelting. All the ore bodies are crossed by small faults, ad- 

 joining which the rock is invariably barren. Knobs of Archaean 

 granite, containing diabase dikes, crop out near the mines both at 

 Mine La Motte and at Doe Run. But the dikes never penetrate 

 the limestone, and were evidently intruded before it was deposited. 



1 J. C. Booth, " Analyses of Various Ores of Lead, etc., from King's 

 Mine, Davison County, North Carolina." Amer. Jour. Sci., i., XLI. 348. W. 

 C. Kerr, Geol of North Carolina, p. 289. 



2 J. D. Whitney, Metallic Wealth. W. W. Mather, New York State 

 Survey, Report on First District, 358. 



