616 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 







The aggregate daily output of the mines whose output has not been indicated 

 in Table I reaches 30 tons, and the average daily output for all the mines may be said 

 to reach from 700 to 800 tons during the year. It will be seen that the smelting 

 capacity of the camp of Leadville is about 700 tons per 24 hours, so that the margin 

 left for the shipment of ore is rather small. 



ORES. 



In Leadville the ore deposits are almost invariably found in limestone, which they 

 apparently have replaced. Table I shows that the ore deposits are only reached 

 through masses of various porphyries, and occasionally, at the outcrops, through 

 limestone. 



Description The ores of Leadville, composed chiefly of carbonate of lead or cerus- 

 site and of galena or sulphuret of lead, are divided into two great classes, the hard 

 carbonates or lumps and the sand or soft carbonates, and each class is subdivided and 

 designated by letters or numbers, according to the assay contents and value. In these 

 ores silver exists chiefly in the state of chloride and of chloro-brouio-iodide. Some of 

 the constituents of the ores have been found in an isolated state; pyromorphite, or 

 chloro-phospbate of lead, and wulfenite, or molybdate of lead, in the Little Chief mine; 

 anglesite, or sulphate of lead, in most mines ; silicate of lead in small reddish crystals; 

 an as yet unknown mineral in the Evening Star mine (this mineral was found by Mr. 

 Emmous and examined by myself, but the quantity was not sufficient to make a com- 

 plete examination) ; ' cerargyrite, or chloride of silver, in the Chrysolite mine, and em- 

 bolite, or chloro-bromide of silver, in most mines ; shapbachite, or sulphuret of bismuth, 

 lead, and silver, in the Florence mine; andbismuthiferouslanarkite,orsulfato-carbouate 

 of lead and bismuth, in the same mine. 



Chief ores The following description will show what are the chief ores in the prin- 

 cipal mines : 



Adelaide. Large crystals of cerussite, cemented by coarse clay. 



Agassiz. Sand. Light-yellow ocher. 



Belcher. Hard. Compact masses of mixed oxides of iron and manganese, im- 

 pregnated with small and indistinct crystals of galena and cerussite. 



Catalpa. Hard. Flinty looking masses of even grain, impregnated with indis- 

 tinct cerussite crystals. This is the typical " hard carbonate" of the camp. 



Chrysolite. Hard. Masses of indistinct crystals of cerussite, cemented by oxides 

 of iron and manganese, both anhydrous and hydrated ; color, brown, reddish, and 

 yellow. 



Crescent. Sand. Pale-yellow ocher and pale-yellow and whitish masses. 



Dunkin. Hard. Fine crystalline galena, imbedded in a hard silicious cement; 

 also distinct and indistinct crystals of galena in a kind of chert. 



Dunkin. Sand. Light yellow ocher. 



Dyer. Hard. Flint, impregnated with galena. 



Evening Star. Hard. Hard carbonate. 



Florence. Sand. Masses with a dull-blackish tinge (bismuthiferous lanarkite), 

 and also shapbachite, with a metallic luster similar to bismuthinite and stibnite. 



Great Hope. Hard. Hard carbonate. 



1 It is probably dechenite, which has since been found in determinate quantity by Dr. lies. 



