4:24 Butler and Sch oiler — Minerals from Beaver Co., Utah. 



In physical properties the mineral corresponds with that 

 previously described. In the hand specimen it is a light green 

 earthv looking material which when crushed in the fingers has 

 a gritty feel like fine sand. Under the microscope it is seen 

 to be well crystallized, the larger crystals being 0'15 nim in 

 diameter. The crystals are golden yellow in color and have 

 the general appearance of being a combination of the cube and 

 octahedron. They are rather strongly birefringent, however, 

 and are probably hexagonal rhombohedral. The index of 

 refraction is higher than l - 74. 



Corkite is readily soluble in boiling hydrochloric acid from 

 which solution lead chloride separates out in quantity on 

 cooling. The solution contains, besides lead, abundant ferric 

 iron and the sulphate and phosphate radicals. Qualitative 

 tests failed to show the presence of any arsenic, and only a 

 mere trace of copper is present in the American corkite. 

 Heated in a closed tube, the mineral darkens and gives off 

 water. 



