GEOLOGY. 801 



LEAD MIXES OF GALENA, ILLINOIS. 



THE Galena Gazette furnishes the following account of a vast ore-bed 

 recently opened about two miles from Galena city. The locality is 

 upon a side hill, where a shaft has been sunk forty feet in limestone, 

 and about as far in "mi?icral." "The mineral now stands up in a 

 perpendicular sheet, about thirty-eight feet in height, between walls 

 of limestone rock, and varies from twenty inches in width to four feet, 

 averaging about thirty-five inches the whole distance. The narrowest 

 places in the crevice are filled with solid, clear, heavy mineral, looking 

 like a mass of conglomerated cubes, measuring from one to six inches 

 on the side. If the rock was cleared away, between which it is 

 wedged, masses, tons in weight, would be instantly detached. Where 

 the crevice opens wider, the cubes of mineral are smaller, and the masses 

 lie detached, between which there is a }*ellow, ochreish earth and clay. 

 One gets some conception of the vastness of the wealth of our mines in 

 such displays as this. How far these masses of mineral extend, or 

 what is the length or height of this perpendicular sheet, beyond what 

 is visible to the eye, it is impossible to determine; it may not ex- 

 tend twenty feet, but the evidence is, when compared with similar 

 leads that have been formerly wrought, that it will run some hundred 

 or even thousand feet. In the latter case, its value is hardly apprecia- 

 ble. About 160,000 pounds have been taken out already, and the lead 

 is considered to have been safely proved for 1,000,000 pounds. Per- 

 haps the best idea we could give miners of the value of the land, and 

 of the size of the sheet, is to say that the owners have drifted about 

 eighteen or twenty feet only westward from where the lead was first 

 struck, and from this space they have raised the 160,000 pounds afore- 

 said. A lead that yields a thousand pounds to a foot is considered a 

 good one ; this, so far, has yielded more than 8,000 to that distance." 



METAMORPHIC CONDITION OF A PART OF THE LARGE YEIN OF FRANK- 



LINITE, IN NEW JERSEY. 



THE following communication was made to the American Associa- 

 tion, Albany, by Mr. A. C. Farrington. 



During the summer of 1848, while engaged in exploring the metallif- 

 erous veins upon w r hat is called Mine Hill, near the Franklin furnace, 

 New Jersey, my attention was arrested by the difference in structural 

 arrangement presented by the opposite sides of the large vein of Frank- 

 linite, at different places along its extent. While much the largest 

 portion of the mass appeared to consist of imperfect octahedral crystals, 

 compacted or cemented, other parts appeared like an aggregation of 

 their lamina, its crystals resenting tabular spar. This latter portion 

 was highly magnetic, and, in pulverizing, I found the hammer would 

 take up large quantities of it. Knowing that other parts of the vein 

 did not exhibit this property, I pursued my investigation for the pur- 

 pose of ascertaining how much of the ore presented this magnetic 

 property. The result was that it was found only where the tabular 

 crystals prevailed, and they calv where the vein w r as in contact with 



26 



