NOTE.'i ON METALLIC MINERALS— SHANNON. 



591 



and derived perhaps from chalcopyrite associated with the pyrite, 

 the lead and antimony yield ratios as follows : 



Pb. 



Sb. 



2603 

 2122 



26.03 4.91 5X0.98 

 21.22 4.00 4X1.00 



It thus seems very probable that the material worked upon by 

 Boulanger, and hence the mineral which should correctly bear the 

 name boulangerite, was of the composition expressed by the formula 

 5PbS.2Sb2S3. 



The name boulangerite was first actually applied by Thaulow ^ 

 to a metallic mineral occurring in straight parallel fibrous masses 

 resembling jamesonite, from Nasaf jeld, Lapland. In column 1 of the 

 following table are given the original figures of Thaulow's analysis ; 

 in column 2 the same analysis with the value for antimony reduced 

 to conform with the value at present used for the atomic weight of 

 that element; in column 3 are given the ratios derived from 

 column 2 : 



Analysis and ratios of ioulangerite from Nasaf jeld, Lapland. 



These ratios yield almost exactly the 5PbS.2SboS3 formula, though 

 showing that the result obtained for antimony is doubtless too low. 



Hausmann- in 1839 described boulangerite from Nertschinsk, 

 Siberia, having the following properties: Massive, with an indis- 

 tinctly fibrous structure like some manganites ; luster, metallic with a 

 silky appearance; color, blackish lead-gray, streak darker; scratches 

 galena but not sphalerite, hence the hardness around 3. Determina- 

 tions of the specific gravity gave 5.688, 5.726, and 5.941, the variation 

 being ascribed to impurities. The specific gravity of the pure min- 

 eral is stated to be not less than 6. The boulangerite was mixed with 

 arsenopyrite, pyrite, and stibnite being often intimately intergrown 

 with the latter. The specimens were crusted with oxidation products, 

 mainly limonite, and waxy to earthy bindheimite. In the following 

 table the analysis made by Bromeis is given in the original form and 

 with the antimony value corrected, together with the ratios as in the 

 preceding tables . 



» Annalen Physik Chemie (Poggendorff's), vol. 41, p. 216, 1837. 



* Hausmann, J. F. L., Ann. Phys. Chem. (Poggendorff's). vol. 46, p. 281, 1839. 



