COLUMBATES, PHOSPHATES, VANADATES 525 



B.B. Kxfoliates, decrepitates, and colors the flame green. 

 Soluble iii H('l, yielding a boric acid reaction with turmeric paper. 



General description. (Yystals prismatic combinations of 

 a, b, c, and m, other forms less prominently developed. Beautiful 

 groups of highly lustrous crystals associated with quartz occur in 

 geodes of tlie massive mineral, to which the terms priceite and 

 pandermite have been applied. 



Colemanite was first discovered in the Death Valley, California ; 

 it also occurs in Nevada, Oregon, and Chili. 



It is the most abundant borate in the California locality, and is 

 the source from which borax and borates are derived. The product 

 or pulp is treated with sulphuric or sulphurous acid, precipitating 

 the calcium, leaving the boric acid in solution, which is recovered 

 in the crude form by evaporation. 



URANINITE 



Uraninite. Pitchblende, U 3 O 8 or (U0 2 )(U0 3 ) 2 ; Uranoso- 

 uranic oxide ; Composition, variable ; Isometric ; Type, Ditesseral 

 Central; Common forms o(lll), d(110), sometimes a (100); 

 Cleavage, none ; Brittle ; Fracture, conchoidal ; H. = 3-6 ; G. = 

 9-9.7 ; Color, pitch-black or greenish ; Streak, olive-green, brown 

 to gray ; Luster, greasy, pitchy, or dull submetallic ; Opaque. 



B.B. Infusible ; with borax or S. Ph. a green bead in R. F. (U). 

 Yields tests for uranium, page 576. 



General description. Crystals are combinations of the octa- 

 hedron, rhombic dodecahedron, and at times the cube ; they are 

 rare ; it usually occurs massive or amorphous, pitchlike in appear- 

 ance. Its chemical composition is variable, some lead is almost 

 always present, and calcium, copper, iron, arsenic, bismuth, tho- 

 rium, cerium, and the yttrium earths may also enter into its com- 

 position. Cleveite, a variety from Arendal, Norway, contains 10 

 per cent, of the yttrium earths. 



It was in uraninite that Klaproth, in 1789, discovered uranium, 

 and Peligot separated the metal in 1842, Klaproth 's product being 

 the oxide UO 2 . It was also from this mineral that Madam Curie 

 separated radium, and it has since been proven that radium and 

 helium contained in the mineral are the results of the breaking 



