514 MINERALOGY 



DESCLOIZITE 



Descloizite. ZnPb(OH)VO 4 ; A basic vanadate of lead 

 and zinc; PbO = 55.4, ZnO = 19.7, V 2 O 5 = 22.7, H 2 O = 2.2; 

 Orthorhombic ; Type, Didigonal Equatorial ; & : b : c = 0.6368 : 

 1 : 0.8045 ; 100 A 1 10 = 32 29' 40" ; 001 A 101 = 51 38' ; 001 A 01 1 = 

 38 49' ; Common forms, a (100), m (110), b (010), o (111), f (201) ; 

 Cleavage, none ; Brittle ; Fracture, uneven ; H. = 3.5 ; G. = 5.9 - 

 6.2 ; Color, orange-red, cherry-red, also shades of brown to black ; 

 Streak, orange to brownish ; Luster, greasy ; Transparent to opaque. 



B.B. Fuses easily ; when reduced with soda, etc., on coal yields 

 malleable lead buttons or a lead coat. Yields a green bead with the 

 fluxes in R. F. and water in the closed tube. Easily soluble in cold 

 dilute nitric acid which yields tests for vanadium, page 576. 



General description. Crystals are small prisms or pyramids, 

 forming drusy surfaces on crusts ; more often amorphous, powdery 

 or earthy. The lead and zinc may be replaced by manganese or 

 iron and at times some of the V 2 O 5 is replaced by As 2 O 5 ; several such 

 compounds have received separate names. 



Descloizite is found at Tombstone and various other localities in 

 Arizona and New Mexico ; also at Leadville, Colorado ; and small 

 quantities have been taken from the Wheatley mine at Phoenix- 

 ville, Pennsylvania. Vanadium minerals are at the present time 

 very valuable, as the vanadium is used in the manufacture of 

 vanadium steel. A very small quantity of vanadium added to steel 

 increases the toughness and the elastic limit without decreasing 

 its ductility. Nickel accomplishes the same result, but vanadium 

 is nearly twenty times as effective. 



CARNOTITE 



Carnotite. KU0 2 VO 4 . 1^ H 2 ; a potassium uranyl vanadate ; 

 K 2 O = 10.37, UO 2 = 63.54, V 2 O 5 = 20.12, H 2 O = 5.95. 



A light canary-yellow mineral, disseminated as a yellow powder 

 through sandstones in Montrose, San Miguel, and Mesa counties, 

 Colorado, and the adjacent counties of Utah. It is easily soluble 

 in acids and yields reactions for uranium and vanadium. It is a 

 valuable mineral, not only for the large percentages of uranium and 

 vanadium it contains, but also for the radium, which is associated 

 with the uranium. 



