OBSERVATIONS IN CHEMISTRY AND MINERALOGY. 423 



temperature above 200° C. in a sealed glass-tube — will brmk up into sulfuric acid 

 and sulfur according to the equation 9 * 



8SO* + aqua - SHtiSO,) + & 



5. On Aurobismuthinite, spec. nov. 



The material appears as a fragment of a plate with nearly parallel aid* 

 must have been the complete filling of a fissure three-eighths of one inch wide 

 one of the parallel faces looks like a black slickenside; there is calcite associated 

 with the mineral. Those who sent me the specimen with the request for 

 information as to whether the gold in it could be extracted with mercury, haw 

 not responded to my request for its locality. The mineral is a granular 

 massive with numerous cleavage planes. These appear to be prismatic, 

 like those of bismuthinite and stibnite. The color of the fresh fracture is 

 light gray, like metallic lead. The mineral is soft and mild, somewhat nnearing 



under the pestle. 



In the open tube it gives much sulfurdioxyd and a yellow sublimate on either 



side of the substance. No reaction for tellurium. On charcoal is given a sof 



white metal, which on the cupel gives a fine gold button with indication of som« 



silver. Gives strong reaction with potassium iodide and sulfur (bismuth). 



Borax bead indicates trace of copper. Rubbing together with mercury does 



not extract any gold. 



The mineral aggregate is very homogeneous. 0.3073 gram gave 0.3130 



BaS0 4 ; 0.2380 Bi 2 3 ; 0.0368 Au; 0.0095 AgCl. 



Bi - 69.50 : 210 = 0.3310 ) 



Au - 12.27 : 197.2 - 0.0622 J-.4039 ■»= 1.0 



Ag = 2.32 : 2 X 107.66 - 0.0107 J 



S = 15.35 : 32 - 0.4800 .4800 = 



leads to the formula (Bi, Au, Ag 2 ) 6 S 6 . 



The view that the normally trivalent gold should replace the equally trivalcnt 

 bismuth has much in it that is pleasing to me, notwithstanding that one is 

 normally isometric and the other hexagonal. If one does not like the ratio 5 : 6 

 one can assume here exactly what is assumed by many for pyrrhotite, namely, 

 that the latter is really FeS and is merely mixed with a varying quantity of 



pyrite, while in present instance m aurobismuthinite (Bi, Au, Agj)S is admixed 

 with n bismuthinite Bi 2 S 3 . In fact the presence of the cleavable prisms might 

 be cited in support of such a view, although the color of the two is exactly alike. 

 There is a third view possible. We may consider gold and silver as an alloy 

 molecularly dissolved within bismuthinite and not united with sulfur. This view 

 is supported by the fact that bismuth is to sulfur as 1 : 1.45, as 2 : 2.9, very nearly 

 2 : 3 which is bismuthinite. Whichever view be taken, the new substance is a 

 very interesting individual and deserves a special name. July, 1908. 



