424 OBSERVATIONS IN CHEMISTRY AND MINERALOGY 





6. On Stibiobismuthinite. 



The material was sent by Mr. H. P. Bowen, a former pupil, in the winter 

 of 1906. The locality of occurrence is the neighborhood of Nacozari state of 

 Sonora, Mexico. 



The specimen appears as an aggregate of large prismatic crystals of the 

 stibiobismuthinite and granular chalcopyrite. Some crystals are two inches 

 long by one-half inch wide ; they look more like sibnite than bismuthinite both 

 for color and dimensions. However the crystals present the usual polysynthetic 

 structure and cleavage. 



In closed tube the mineral melts easily and gives a strong sublimate of sulfur 



a slight red sublimate of antimonyoxysulfid and a slight sublimate of metallic 



antimony. In the open tube strong white fumes of antimony trioxyd, and 



even here a slight sublimate of sulfur. With potassium iodid on charcoal strong 

 red film of bismuth oxyiodid. 0.3633 gram gave 0.3160 BiOCl and 0.0411 Sb 2 S 3 . 



Bi = 69.90 : 210 = 0.3330 \ n ooqc _ i nn 



Sb = 8.12 : 122 = 0.0665 J u ^ yy{> ~ 1,uu 



S « 21.92 (by difference) : 22 = 0.6869 = 1.72 



100.00 



The nearest ratio with whole numbers is 4 : 6.88, which makes the formula 

 (Bi, Sb)4S 7 . 



The strong sublimate of sulfur in both open and closed tubes indicates the 



presence of a higher sulfid than 2 : 3, as in bismuthinite. 



■ 



7. On Crystallized Seladonite. 



The specimen was sent by Mr. Grant, a former pupil, to Professor Seaman, to 

 whom I am indebted for it. It is said to come from near Vail, Arizona, about 4 

 miles east of that town, where it comes in basalt and basaltic tufas. The sela- 

 donite is associated with reddish gray calcite. Even when examined with the 

 lens, the seladonite appears to form soft masses without distinct shape. When 

 such a mass is digested with water or only stirred up with the liquid; the mass 

 disintegrates into minute green prisms. This enabled me to get the materia 

 to a high state of purity, since the only other mineral present is calcite. 1 e 

 prisms are 0.01 mm. long and 0.0005 broad. They show pyramidal development; 

 the outlines are not sharp, apt to show undulation. There is also a tabular type. 

 The color of these prisms and plates is pale olive green under water, bluis - 

 green in air. . ^ 



The true hardness cannot be ascertained; the apparent hardness is tna o 

 any felted or pulverulent substance. The color of the large aggregate is 

 peculiar blue-gray-green also known as l * seladon green ." , 



B. B. In tube gives water and turns brown. With fluxes reacts oy 

 for iron. Acted on slowly by concentrated hydrochloric acid. Fuses to g 

 at yellow heat. 



