202 NEW YORK STATE MUSEUM 



cent ore is very high grade, though some ore runs 60 or 70 per 

 cent. 



Carnotite. Carnotite is an amorphous, soft, powdery material, 

 sometimes more or less coherent and of a talcose or waxy character, 

 generally of a brilliant canary yellow color, though sometimes dis- 

 colored by iron, organic matter and other substances. It has a 

 formula K 2 0.2U0 3 .V 2 05.(?)H 2 0, in which the amount of water 

 (H2O), has been variously estimated at from 3H2O to 8H 2 0. It 

 is essentially a hydrous potassium uranium vanadate and is some- 

 times associated with the hydrous calcium uranium vanadate known 

 as tyuyamunite, having the composition Ca0.2U0 3 .V 2 5 (?)H20 in 

 which the amount of water is uncertain, as in carnotite. Some 

 authorities believe that carnotite is not a distinct mineral, but a 

 mixture of different minerals. 



Uraninite and pitchblende. The terms uraninite and pitchblende 

 are often used synonymously to designate the same mineral, but 

 more properly the term uraninite is a general name for all forms of 

 the mineral and especially for the purer and distinctly crystalline vari- 

 ety, and the term pitchblende is applicable to the impure amorphous 

 form. When crystalline, the mineral belongs to the isometric 

 system, and when amorphous is in a massive form, often with 

 botryoidal surfaces and a conchoidal fracture. It is black or grayish 

 black in color, opaque, often has a submetallic, glossy or pitchlike 

 luster. It has a hardness of about 5.5, and a specific gravity of 

 9 or over when pure, but both these qualities vary when the mineral 

 is impure. It is often remarkably lacking in distinctive character- 

 istics, so that its presence might frequently be overlooked. For 

 this reason it seems possible that this mineral, now known in only 

 comparatively small quantities, may some time in the future be 

 found more abundantly. 



Uraninite, like carnotite, has a somewhat indefinite formula, but 

 is essentially a combination of the two uranium oxides U0 2 and 

 U0 3 , in which U0 2 seems to act as a base and U0 3 as an acid. A 

 number of both the rarer and commoner elements are often asso- 

 ciated with them. The relative amounts of the two oxides vary 

 considerably in different specimens, especially in the impure form 

 of pitchblende, and no definite formula can at present be given. 

 In pitchblende a notable amount of water, perhaps sometimes in 

 chemical combination, is often present. Several other minerals 

 much rarer than uraninite or pitchblende are related to them in 

 composition, among them being cleveite, broggerite and nivenite, 



