254 



Third Supplement to Dana's Mineralogy, 



Erubesctte [p. 38]. — Analysis of ore from Coquimbo in Chili by W. Booking 

 (Ann. Ch. u. Pharm. xcvi, 244) : — Sulphur 25-46, copper 60-80, iron 13 67=99'93. 



Feldspar [p. 228, and Suppl. i, n]. — Analyses (1 to 4) of Glassy Feldspars, by 

 Dr. G. Lewinstein (Ueber die Zusamm. des Glas. Feldspaths, etc., Berlin, 1856). No. 



1 from volcanic sandj 2, 3, 4, from trachyte and trachytic conglomerate : 



Si £1 £e Ca fig Na K 



1. Rokeskill, Eifel, 66 65 18 91 149 0'76 4 45 7-74=100 G=2'578 



Oxygen, 35 28 8'83 042 031 115 1'31 



2. Perlenhardt, [65 26] 17-62 091 1'05 0'88 2-49 11-79=100 

 Oxygen, 3394 8-23 0 30 0-29 035 0"64 T96 



3. Drachenfels, [65 59] 16 45 1 58 0-97 0 53 2 04 1 2-84=100 G.=2"60 

 Oxygen, 3440 7'69 0 47 027 0"20 0-52 2 17 



4. Pappelsberg, [66-03] 17 87 0 52 0-47 0-19 6 08 8 86=100 G.=2'616 

 Oxygen, 34 28 8*35 0'16 013 0 07 1-55 1*50 



In No. 3, the silica as directly determined equals 66-12. 



The analyses give quite closely the orthocla^e formula, it Si -4- 35 Si 8 . _If the iron 

 be taken as protoxyd, the analyses correspond as well to the formula 9R Si-f-7fi Si 8 . 



Ch. Heusser refers the Hyalophan of Waltershausen [Suppl. i], to Adularia 

 (Pogg. xcvii, 128). It occurs in the dolomite of the Binnen valley, and agrees with 

 that species in physical and crystallographic characters. The 2 28 p. c. of sulphuric 

 acid found by von Waltershausen he attributes to mixture with pyrites, which is 

 common in the rock in minute crystals. In seven different crystals examined with 

 the blowpipe, he found no trace of sulphur. Moreover dolomite and heavy spar 

 often occur as other impurities and partly may account for some of the results hi 

 the analysis. 



The Weissigite of G. Jenzsch has afforded him (N. Jahrb. f. Min. etc. 1855, 800) : 



Si £1 Mg Ca K Li Fl,loss. 



1. 65-00 19-54 1-61 0-19 12 69 0"56 0-35 =99'94 



2. 6521 19-71 055 



The weissigite occurs in amygdaloidal cavities, in layers with chalcedony, etc. 

 No. 1 is from the oldest or lowest of two layers, the color flesh red ; G. = 2-551 — 



2 553. No. 2 is from a second layer ; color paler rose-red to reddish- white ; G. = 

 2*533 — 2*553. The oxygen ratio for the protoxyds, peroxyds and silica in No. 1 is 

 3 - 15 : 9 13 : 33 - 75, which is near the orthoclase ratio. Part of the Weissigite No. 2 

 is pseudomorphous after Laumontite. 



The analysis of No. 1 above comes nearest to the feldspar of Radeberg (see 

 Suppl. ri, under feldspar). 



The same amygdaloidal cavities contain the chlorophanerite and the weissigite. 



G. Bischof obtained (Lehrb. Geol. ii, 2171) from a feldspar pseudomorph after 

 Laumontite from the Kilpatrick Hills (where others occur with the form of anal- 



Si £1 £e Ca Mg K STa ign. 



62-00 20 00 0-64 0*60 trace 16-54 1-08 087= 10P72 

 Oxygen, 32 19 9-35 0-19 0 17 281 0 27 



• Fergdsonite.— See Tyrite, this Supplement. 



Freislebenite [p. 79]. — A mineral which has been referred to Freislebenite and 

 is probably near Bournonite, is described as new by Kenngott, in Pogg. xcviii, 165. 

 Occurs in thin 4-sided tables (2 millimeters thick and about 12 across) of the mono- 

 clinic system, with two planes making up each margin of the table. Acute plane 

 angle of base about 42°. H.=2 5. G =6-06. Color iron black, streak black. Brittle. 

 B.B. fuses easily to a black shining globule and yields finally a globule of silver. 

 The silver constitutes about 30 per cent. The charcoal becomes covered with fumes 

 of antimony and lead, and the mineral probably consists of silver, lead, antimony, 

 and sulphur. 



