110 S. L. Penfield — Oan/ieldite, a new Germanium Mineral. 



weighing about five and six grams each, carefully taken on a 

 chemical balance after boiling in distilled water, was found to 

 be 6 '2662 and 6*2657 respectively, the temperature being 25° 

 C. The specific gravity of the fragment containing the crys- 

 tal that was measured and weighing over 22 grams was found 

 to be 6-270. The luster is brilliant metallic. The color black 

 with a blueish to purplish tone. The streak is grayish black, 

 somewhat shiny. The chief pyrognostic properties have 

 already been given. In addition the fusibility at about \\ to 

 2 should be noted. The fused transparent globules which 

 were observed on charcoal are probably Ge0 2 . Some of the 

 oxide separated from the quantitative analysis was tested on 

 charcoal as follows : In the oxidizing flame it fused with bub- 

 bling to a transparent, glassy globule, giving no coating. By 

 continued heating in the reducing flame it darkened and gave 

 slowly a pure white sublimate. The yellow coating obtained 

 on charcoal from the mineral was probably a mixture of oxide 

 and sulphide of germanium. The fused globules, which were 

 observed near the assay in the closed tube are GeS 2 or possibly 

 some oxysulphide. Argyrodite, when tested in the closed 

 tube, gives at first a black sublimate, which as stated by 

 Richter,* looks exactly like mercuric sulphide and undoubt- 

 edly is that substance. On intense heating before the blow- 

 pipe there formed farthest up on the tube a sublimate of sul- 

 phur, next followed the black ring of mercuric sulphide, 

 neither of which increased perceptibly by continued heat- 

 ing, while nearest the assay the nearly colorless globules of 

 GeS 2 were deposited. On breaking off the lower end of the 

 tube, driving off the sulphur and mercuric sulphide by gentle 

 heat and then roasting the globules in a current of air, S0 2 

 was given off while the germanium oxide collected into a fused 

 mass but was not volatilized. Regarding the association of 

 canfieldite with other minerals, all that can be said is that the 

 specimens are remarkably pure, only slight quantities of pyrite, 

 sphalerite and kaolin being attached to them. 



It having been shown that the mineral was essentially a 

 sulpho-salt of germanium and silver, the following method 

 was adopted for analysis. A weighed quantity, about two 

 grams, was oxidized by concentrated nitric acid, the operation 

 requiring from one to two hours on the water bath. After 

 the oxidation was complete the excess of nitric acid was re- 

 moved by evaporation. The residue was then dissolved in 

 warm water slightly acidified with nitric acid, and after filter- 

 ing off a slight trace of insoluble residue the silver was pre- 

 cipitated by hydrochloric acid, filtered and weighed. In the 



* Quoted by Weisbach and Winkler. Log. cit. 



