S. L. Peuiield — Canfieldite, a new Germanium Mineral. 109 



from which solution the addition of acid, especially in large 

 excess, precipitated a white sulphide. On heating some of 

 this sulphide in a tube through which a current of hydrogen 

 was passed, small glittering scales of GeS, in luster resembling 

 hematite, were formed just beyond the ignited material. These 

 on examination with the microscope in transmitted light were 

 found to be dark brown in color. Although not mentioned by 

 Weisbach* it was noted that these were strongly pleochroic, 

 the direction of greatest absorption being at right angles to 

 the longest axis of the plates. By continued and higher heat- 

 ing a still further reduction took place and metallic germanium 

 was deposited as a crystalline sublimate on the walls of the 

 tube. Microscopic examination showed this sublimate to con- 

 sist of small gray-white octahedral crystals of magnificent 

 metallic luster. They were found, to be insoluble in hydro- 

 chloric acid but were readily dissolved by aqua regia. These 

 results agree exactly with those given by Winkler and. the 

 identity was still further confirmed by the entire behavior of 

 the element and by other results which will be given in the 

 course of this article. 



The physical properties of this new mineral are as follows : 

 Crystallization isometric. Among the specimens furnished by 

 Mr. Canfield were two which were well crystallized. One of 

 these consisted of a group of unmistakable octahedral crystals, 

 averaging about 7 mm in axial diameter, but which were too 

 rough for measurement on the goniometer. Their edges were 

 sometimes truncated by the dodecahedron, while some were 

 twinned about an octahedral face. The other specimen con- 

 tained equally large but less isolated crystals, the luster of 

 whose faces was good and one of the crystals, showing the 

 four upper faces of an octahedron, with edges truncated by 

 the dodecahedron was measured on the reflecting goniometer as 

 follows : 



111 ^111 = 70° 0' 



111 ^ 111 = 70 29 



111^111=70 14 111 yv 111 = 108° 57' 



111 ^ 111 = 70 8 111 „lll = 109 3 



Calculated, 70 32 Calculated, 109 28 



The reflections of the signal were moderately good and con- 

 sidering a slight rounding of the faces the measurements agree 

 as closely to those of the octahedron as could be expected. 

 The dodecahedral faces were too uneven to yield a distinct 

 reflection. These crystals were tested and found to give the 

 characteristic reactions for germanium. The fracture is irregu- 

 lar to small conchoidal. Extremely brittle. Hardness about 

 2*5. The specific gravity of two distinct, massive fragments, 



* Quoted by Winkler, loc. cit., p. 215. 



