Pearceite and Polybasite. 43 



1. Guarisamez, Durango, Mexico, H. Rose, Pogg. Ann., xv, 575 

 1829. 



2. Freiberg, Saxony, H. Rose, Pogg. Ann., xxviii, 158, 1833. 



3. Cornwall, Joy, cited by Rammelsberg, Mineralchem., 5 

 Suppl., 1853, 194. 



4. San Pedro Nolasco, Tres Puntes, Chile, Taylor, Proc. N. Sc. 

 Phil., Nov. 1859. 



5. Pribram, Bohemia, Tonner, Lotos, 1859, 85, and Neues 

 Jahrb., 1860, 716. 



6. Tres Puntes, Chile, Domeyko, Min., 1879, 391. 



7. Al Finhallada, Tres Puntes, Chile, Domeyko, Min., 1879, 391. 



8. Terrible Lode, Clear Creek Co., Colorado, Genth, Amer. 

 Phil. Soc. xxiii, 39, 1886. 



9. Santa Lucia mine, Guanajuato, Mexico, Prior, Min. Soc, 

 Lond., ix, 14, 1890. 



10. Quespisiza (Chile?), Peru, Bodlander, Neues Jahrb., i, 99, 

 1895. 





1 



2 



3 



4 



5 



6 



7 8 



9 



10 



s 



17-04 



1635 



15-87 



16-14 



15-55 



1610 



15-30 (16-70) 



15-43 



16-37 



Sb 



509 



8-39 



546 



11-55 



11-53 



4-20 



9-50 10-18 



1064 



515 



As 



3-74 



1-17 



3-41 







4-10 



.... 0-78 



0-50 



3-88 



Ag .... 



64-29 



6999 



72-01 



6418 



68-55 



64-30 



62-10 62-70 



68-39 



67.95 



Cu .... 



993 



4-11 



3-36 



8-13 



3-36 



9-00 



6-00 9-57 



5-13 



6-07 



Fe 



Pb .... 



Insol 



006 



0-22 



0-34 







0-34 



0-70 



1-10 0-07 







0-76 



.... 



.... 



.... 



.... 



.... 



i : 60 



6 : 66 '.'.'.'. 



.... 



100-15 100-30 100-45 10000 99-13 100-00 100-00 100-00 10009 100-18 

 Sp. G. . 6-214 .... 6-0302 6-009 6-33 .... 



In analyses 6 and 7, the insoluble matter was deducted and the 

 analyses recalculated. The same method was followed with 

 the lead in 10. The same atomic weights were used as in the 

 calculation of the pearceite, and the following combining ratios 

 were found : — 



Analysis S (Sb,As) (Ag 2 Cu a Fe) 



1. Gaurisamez, Rose, 1829 11-524 2 8-176 



2. Freiberg, 1833 11-938 



3. Cornwall, 1853 10*898 



4. San Pedro Nolasco, 1859 10-482 



5. Pfibam, 1860 10-110 



6. Tres Puntes, 1879 11*224 



7. Al Finhallada, 1879 12-070 



8. Terrible Lode, 1886 10-960 



9. Santa Lucia, 1890 10-096 



10. Quespisiza, 1895 10*800 



An inspection of the ten ratios shows that seven of them 

 (3, 4, 5, 6, 8, 9, 10) conform more closely to (Ag,Cu) 16 Sb a S n 

 than to (Ag,Cu) w Sb 3 S ia . Furthermore in 1, which was the 



2 



8*470 



2 



8*062 



2 



7*526 



2 



7*202 



2 



8*498 



2 



8*970 



2 



7*726 



2 



7*398 



2 



7*676 



