k 



4 



Fourth Supphyneiit fo Danas Mineralogy, 129 



Siegert's anatysis of Stilpnomelane gave Si 420Y, Pe 41-98, Si 4'92, Sfg 0*94, Ca 

 1-67, H 8-47=100 05. Sec Rammelsberg's 5th Suppl., 230, and Dana's Mia, p. 288 



TACHIIYDPvITE, Rammehhcrg (Pogg. xcviii, 261). — A compound of chlorid of 

 ^ lime and chlorid of magnesium, of the formula CaCl-f-2Mg Cl-|-12ll. Analysis 



afforded Rammelsberg : — 



CI Ca Mg ' ft 



40-34 7-46 9-51 42-69 = 100 



Occurs in the salt mine of Stassfurth associated with anhydrite, in roundish masses, 

 transparent to translucent, and of a yellow color. It has at least two distinct cleav- 

 ages. The name alludes to its ready deliquescence on exposure.. 



The same locality affords the Martinsite, a granular mixture of chlorid of sodium 

 (90 p. c.) with sulphate of magnesia and anhydrous [ilin., p. 90], There is also a 

 sulphate of magnesia of similar appearance containing but little more than 1 p. c. 



of water (AlgS+aq.). The analysis afforded Rammelsberg, S 57'7, Mg 26-8, water 

 15'5. It is mixed with 4 per cent of chlorid of sodium. 



Tantaltte [p. 351, and III]. — Analvsis of the tantalitc of Kimito by Hermann 

 (J. f. pr, Ch., Ixx, 205): Tantalic acid (¥a) 7307, columbic-acid (€b) 11-02, Fe 10-08. 

 Fe 3-33, Mn 1-32, Sn 0-70=99-70. 



The tantalite from Chanteloube, afforded C. F. Chandler (luaug. Dissert.), Ta 79-89, 

 Sn 1-51. 2r 1-32, Fe 1414, Mn 182, Ga, Cu ?race=98-67. Probable oxygen ratio 

 for K,Ta, 1:5. G.=7-533. 



Topaz [p. 259, 512]. — Kokscharov has given a large number of fine figures of 

 I Russian crystals of topaz in his Min. Russl. (ii, 198, and plates xxix to xxxviii inclu- 



sive). He mention? the planes 2-2^ 1-5^ 1-q6, 3-oo, i-^-oo ? and ^-2, which are not 



mentioned in the Mineralogy. [In these symbols, the fundamental pyramid (1) ia 

 I that which gives 0:1=134*^ 32^ — taken a^ the pyramid 2 by Kokscharov.] — Ac- 



cording to Kokscharov's measurements, /: 2=153° 53' {153° 54' 8" Calc), O : g= 

 145°47'(145°55'Calc.), |: | (macrod.)=149° 32' (149° 31' Calc), tj : 22=^3^ 

 12' (93° 10' 44'' Calc), 7: ^2 (over /)— 105° 34' (105° S3' 8" Calc), 2T : 2^ (over 

 top)=92°42' 15", O:2T=13r»°20'47", : 2T=rll8° 59' 0", : 1=134° 24' 38", 

 /; 1=135° 35' 10", 7: 7=124° 16' 40". In 4 crystals from the Ilmengebirge. the 

 variation for 7: /was only 1', the measurements giving 124° 16' 10", H5' 30", 17' 

 0", 16' 0". The angles considered the best for calculation, are 7: 7=124° 17', and 

 0:2^=1360 21'. 



r" 



TouniTALTXE [p. 270, and II].— Green tourmalines occur in the valley of Harrach 

 In Algeria. — BulL Soc. Geol. de France, [2], xiii, 416. \ 



TvRiTE [Suppl. I, III]. — The question of the reference of Tyrite to Fergusonite 

 by Keungott is shown by D. Foid>es (Phil. Mag.» [4j, xiii, 91) to require more inves- 

 '^ tigation. The crystrrts are stated by Forbes to be too rough and imperfect for exact 



measurement, yet, it is observed, the form may turn out to be tlic same. The spe- 

 cific gravity is different, being about 05 higher in Fergusonite. The composition ac- 

 cording to the analyses is different. The foMowing are the results of two analyses 

 i by D. Forbes, and one of Fergusonite by Hartwa!!. The metallic acid of the fergu- 



\ sonite is not known certainlv to be tantalic, although so stated. 



Sn 



Xl 



2r,& 



^^ 





566 



trace 



4-52 



trace 



355 



2 78 



4-66 



100 





302 



trace 



Cb , Y Ca (5e La Fe tJ 



1. FromHampemyr, 44-W 2972 81 5-35 626 303 

 2.FromHelle, 4448 27-83 168 5 63 1-47 211 5*99 



2. Fergmonile, 4775 4r3l — 4 6^ FeO-34 Fo-95 



The Fergusonite was examined for water by Hartwall, but none found. Tlie Tyrite 

 crystals appeared to be fresh. They are tetragonal and have their bases in crystals 

 of black mica, and often taper to a point, without facets. One cleavage distinct, 

 and traces of two otliers. H.:=6"5. Brittle. G.=5-36; another crystal not so dig- 

 tinct in cleavage, 513. Crystals occasionally 2 inches long. They come from Helle 

 on the mainland at Nxeskiil, about 10 miles east of Arendal, and at Ilampeaiyr on 

 the Island Tromoe. 



SECOND SERIES, VOL. XXIV, NO, TO. — JULY, 1S67, 



17 



