II ". 1\ Blaki — Min, ralogioal Nb& & 43 



Physical characters. — Specific gravity (in powder), 4*56, 

 1*59; hardness, 2*5; fusibility, l - ; luster, dull; color, bright 

 rod ; streak, orange-red : fracture, cubical. 



From the cubical fracture of the minium, resembling that of 

 galenite, and the occurrence of galenite in the red minium, it 

 would appear that the minium here is a pseudomorph after 

 galenite The vanadic oxide which was found in the mineral, 

 no doubt existed as vanadinite, which has been frequently 

 found in Leadville. 



The occurrence of sulphide of lead in the pure mineral is 

 rather remarkable and also suggestive. Externally the particles 

 of minium showed no evidence of the presence of any other 

 mineral; it was not until the powdered mineral had been 

 treated with hydrochloric acid and all Pb 3 4 dissolved, that the 

 galenite could be observed. This seems to be conclusive evi- 

 dence that the minium in this case, was a direct alteration from 

 galenite. A like deduction is forced, as regards the plattnerite 

 lately found in the Cceur d'Alene Mts., Idaho, where all the 

 lead ore is sulphide. 



Laboratory of the Globe Smelting and Refining Co. 



Art. VII. — Mineralogical Notes ; by William P. Blake. 



1. Thenardite, Mirabilite, Glauber ite, Halite and associates, of 

 the Verde Valley, Arizona Territory. 



The deposits of sulphate of soda of the valley of the Verde 

 river near the military post of Camp Verde have long been 

 known, and extensively quarried, by the ranclieros of the region 

 as a substitute for salt for cattle and horses. The occurrence 

 of thenardite in Arizona was tirst made known to science by 

 the late Prof. B. Silliman, in 1881,* but he had not visited 

 the localitv and it has not been described. A recent visit to 



%J 



the place, and a somewhat hurried and superficial examination, 

 enabled me, however, to collect and identify other allied spe- 

 cies in association with the thenardite, and a peculiar pseudo- 

 morph of carbonate of lime after glauberite. 



The deposits of the thenardite and the associated minerals 

 are of considerable magnitude, covering several acres in 

 extent, and reach a thickness of some fifty or sixty feet or 

 more. They appear as a series of rounded hills with sides 

 covered with a snow-white efflorescence and a greenish-colored 

 and yellow clay at the bottom and top, partially covering the 

 saline beds from view. 



*This Jour., xxii, 204, 1881. 



