Butler and Schaller — Minerals from Beaver Co., Utah. 419 



was not seen in place, but the frequency with which it was met 

 in the old dump leads to the belief that it must have been a 

 rather common mineral in some parts of the deposit. 



Physical Properties. — The mineral is a canaryTyellow earthy 

 looking material commonly mixed with other secondary lead 

 and copper minerals, but occasionally in small masses that 

 appear to be composed of a single mineral. Such masses are 

 easily crushed in the fingers. Under the high power of the 

 microscope the material is seen to be crystallized in distinct 

 hexagonal plates. These are too small for accurate measure- 

 ment of the crystal angles or determination of the optical 

 character. The refractive index of the light ray vibrating per- 

 pendicular to the plates is considerably higher than that of 

 solutions available in the laboratory for the immersion method 

 of determining indices, namely 1*74. 



Almost every crystal contains a minute inclusion whose 

 character has not been determined. The material analyzed 

 appeared under the microscope to be very pure except for 

 these inclusions, and it is possible that the silica that appears 

 in the analysis is due to them. 



Chemical Composition. — The mineral is soluble in boiling 

 hydrochloric acid, leaving the insoluble matter, chiefly silica, 

 behind. On cooling, lead chloride separates out in considera- 

 ble amount. The lead reaction can also readily be obtained 

 with sodium carbonate on charcoal. On adding ammonia in 

 excess to the hydrochloric acid solution, the ferric iron is 

 thrown down as a voluminous brown precipitate, and the solu- 

 tion has the deep blue color indicative of copper. By the 

 quantitative determination, the presence of a small amount of 

 alumina was established. The insoluble matter consists mostly 

 of silica, only a slight residue remaining after treatment with 

 hydrofluoric acid. 



The average of the results of the chemical analyses is shown 

 in the table below. The ratios obtained therefrom are also 

 given. 



Analysis and ratios of beaverite ( W. T. S.). 



Insol 10-05 



CuO 9-70 -121 -92 or 1 



PbO 29-44 -132 1-00 " 1 



FeO .... 17-28 -108) „ 



A1.0,.... 3-64 -036 j 144 l m l 



S0 3 21-32 -266 2-01 " 2 



H a O 9-02 -501 3-80 " 4 ( = 4x-95). 



100-45 



The ratios agree well with the formula CuO.PbO.Fe 2 3 . 

 2S0 3 .4IT„0, in which the copper and lead are assumed to be 



Am Jour. Sci.— Fourth Series, Vol. XXXII, No. 192.— December, 1911. 

 31 



