CHARACTER OF ORES. 25 



silver are very various, running from 20 up to 200 ounces per ton of 

 crude ore. The percentage of lead also varies, though (JO to 70 per cent is 

 a common value. The lead occurs mostly as a sulphide (galena), some- 

 times as a carbonate at shallow depths. The ores also carry a varying 

 quantity of arsenic, antimony, iron, and zinc in diverse combinations. 

 The lead silver veins are remarkable for their great length, many hav- 

 ing been traced 10 to 20 kilometers (0 to 12 miles), but outcropping ore 

 deposits are only found at long intervals. The balance of the vein is 

 either ''blind" — that is, it does not break through the overlying coun- 

 try rock so as to be visible on the surface — or it spreads out and becomes 

 "banded,'" in which ease it is supposed to carry no ore. Veins of this 

 class have in a measure the appearance of true fissures. None has been 

 worked deep enough to be exhausted. They are often very wide where 

 the ore bodies are found and have the appearance sometimes of cham- 

 bered deposits. Their surface croppings are iron in various stages of 

 decomposition, the so-called "iron cap." The thiekness of this varies 

 from 10 to 30 meters (33 to 100 feet) or more, depending upon the amount 

 of surface wear to which it has been subjected. 



The auriferous deposits embrace placers and lodes. The placers do 

 not differ essentially from similar mineral deposits in any other region. 

 A great deal of the placer ground of the Cuuir d'Alenes remains 

 unworked, by reason of the heavy expense entailed in dealing with the 

 subwater, which is struck before bed rock or pay dirt is reached. 



The auriferous quartz veins are both pyritiferous and free gold bear- 

 ing. Both kinds of ore are usually found in the same vein. The lodes 

 are narrow and very frequently present the appearance of blanket 

 veins, a feature which is apt to cause some doubt as to their capacity 

 to hold out under long-continued working. There are no very deep 

 excavations on them as yet; hence this point is unsettled. The free 

 gold in these veins will probably turn to salphurets when a sufficient 

 depth is reached. 



The cupriferous silver lodes are not very common. They have been 

 found in the basins of the South Fork, North Fork, and St. .loseph 

 rivers, but have been explored comparatively little. Generally their 

 croppings consist of chalcopyrite or its oxidized or carbonized com- 

 pounds. The richest ores produced by this class of veins are usually 

 compounds of silver, antimony, and lead in varying proportions. 



To sum up the mineral resources of the Cceur d'Alenes, they embrace 

 gold, silver, copper, lead, and antimony, as well as most of the other 

 commercial metallic elements. In the developed districts the four first 

 named occur as great and lasting deposits. 



AGRICULTURAL CAPACITY. 



The areas fit for agricultural pursuits in this region are very limited 

 in extent. By far the larger portion of the valleys and canyons are 

 narrow and rocky and utterly unsuitable for farming purposes. The 

 best and most extensive acreage of tillable land is found in the lower 



