218 Tenth Supplement to Dana's Mineralogy. 



Platinum [p. 12, 11, Til, VT, VIII].— B. Cotta has observed platinum, assoeiat^lj 



PoLYBASiTE [p. 85].— Analysis of polybasite, from Przibram, in Bohemia, by 

 Ag Cu Fe Sb S ^ 



Lotos, 1859, 85, in Jahrb. Min., 1860, 716. 



Pbkhnite [p. 314].— Nofjgerath describes the occurrence of prehnite, associated 

 with fluor-spar, from Fassathal, in Tyrol {Sitzung^ber-ichte der niederrlieinischen (xeuU^ 



Procstite [p. 18, IX].— Dr. Genth has discovered microscopic crystals o(prouMe, 

 associated with native .silver, at the McMakin Mine, Cabarras Co., North Carolina, 

 [this Journal, [2], xxxiii. 195). 



PsiLOMELANE [p. 135].— Analysis of psilomelane, from Loeh Mine, near Olpe, by 

 SinSn Cu Co ()a S fl In^o'- 



Pyrope [p. 194].— F. A. Genth has analyzed the pi/rope from near Sante le.^^ew 

 somewhat angular grams, fromVtoT^"cherin Xmeter^ gS:3-738. Composition: 



Si XI ^8r fe Sin Ca Mg Ign. __ ^^^^ 



Considering the chrome as sesquioxyd, and the iron as protoxyd, the oxygen ratio for 



Pyro-smalite [p. SlO.-This rare species has been reexamined by J. U^S (;f<^"J 

 Wermland, and occurs there in hexag<;nal prisms, of sometimes an mch ^^^^^4. 

 Decomposed by both nitric' and chlorhydric acid. The mean of all the determina- 

 tions, including two complete analyses, gave : 



Si Fe Kin Si Ca Cl H 



35-43 3072 2051 0-24 0-74 3-79 '7'?5 



A special determination showed that only 0-79 of the iron was sesquioxyd^; *« 



protochlorid of iron, and a .silicate of protoxyd of iron. The formula may be written 

 3Fe Cl+4 (il3 gi+2R3§i3_^6fi). 



PvRoxENE [p. 158, 1, IT, V-IX].- Analysis of pyroxene, from the Vesnvian lavjoj 

 I858,^gave^ Rammelsberg gi 49 61, Si 442, Fe 9-08, Ca 22 83, Mg 14 22, ¥e uadet 



" ronzit^^!n>^K 



,rmaDdopf«J 

 ieudoinorpb, fj 



by opticll examination, that ensiatite, bronzit^^fP^^^ 





J^a«,l mum. a compact variety of PTfJ 

 itlrid^Sal^S'SrSr^e^ 

 c characters. Since the publication oftw* 

 f so-called steatites, and have found among 



