52 



Comparison of aneroids Xos. 22 and 37 with standard mercurial cistern-liaromeler at office of Bet. Col. H. S. TriUiam>ion, Corps 



of Engineers, San Francisco, California. 



MINERALS. 



Siuce tbe ilifl'erent forms in which the elements of lauded surface are aggregated determine 

 whether we shall have a region agricultural, mineral, or arid, as may be expected, the greatest 

 diversity occurs, and experience teaches that agricnltnral and mineral sections are seldom found in 

 immediate juxtaposition. 



Southern Xevada undoubtedly possesses all the rights and privileges of a mineral region, and 

 beyond that, as a place for tlie aggregation of population, it must always have small weight in com- 

 parison to other land-areas of equal size. I do not hesitate to say that the section embraced be- 

 tween the 11-lth and 116th degrees of longitude, limited latitudinally by '66° 30' on the south, and 

 39° 30' on the north, bids fair to develop and supi)ly more of the precious metals than any 

 similar-sized area covered by our survey. 



The minerals found are gold, silver, copper, lead, antimony, iron, salt, gypsum, alum, and 

 cobalt; of them all, silver is the most common, and is the principal of the precious metals in all 

 the different mining camps, while, so far as the knowleilge is at my disposal, gold is only noticed 

 at the Sacramento, Egan, and Groom Districts, and, except at Egan, only in small quantities. 



Silver-ore appears in all its iiiiown forms, the more common being the chloride and sulphide- 

 Sulphide is becoming common and rapidly growing into significance as one of the richer das.ses 

 of ore, and many a black-looking rock, that would have been thrown away by the early prospector, 

 is now found to assay as high as $3,000 or $4,000 per ton. Copper is found native and in the ore 

 n the Potosi and Clarke Districts, and at various points along and near the Colorado River; lead, 

 as sulphurets, always more or less argentiferous, in some i^laces appears in immense deiiosits and 

 veins; these can all ultimately be worked, and to a good profit; the base bullion averaging tioni 

 $35 to $2(i() per ton. 



Antimony occurs also with the galena, sometimes to so great an extent as to render flic free- 

 ing of the silver-ore a diflicult problem. 



Gyi)snm is found in beds at two places noticed by our parties ; one not far from the old emi- 

 grant-road, and about midway between Las Vegas ranch and the crossing of the JIuddy ; and at 

 another along Las Vegas Wash. The (piality is apparently inferior. 



