TROOSTITE. 

 Teoostite, Shepard, Mohs, Nicol. A 

 variety of Willetnite containing 2-0 per 

 cent, of oxide of manganese. Hexagonal. 

 Also massive and granular. Colour aspa- 

 ragus-green, also yellow, grey, and reddish- 

 brown. Transparent to opaque. Lustre 

 vitreo-resinous. Brittle. Fracture conchoidal. 

 H. 5-5. S.G. 4 to 41. 



Comp. 2Mn3 Si" + Fe^ 812. 



A.nalysh, by Thomson : 



Protoxide of manganese . 46-22 



Silica 30-65 



Protoxide of iron . . 15-45 



Water and carbonic acid . 7-30 



99-62 



BB fuses at the edges ; imparts a faint 

 violet tinge to borax. 



Locality. Xew Jersey. 



Name. After Dr. G. Troost, Professor of 

 Geology in Nashville College, Tennessee. 



Brit/Mus., Case 28. 



TscHEFFKiNiTE, Dana. See Tschew- 



KINITE. 



TscHERMiaiT, Kenngott. A kind of Am- 

 monia-Alum. 



It occurs compact and lamellar. Colour- 

 less or greyish-white. Lustre vitreous. 

 Transparent to semitransparent. Brittle. 

 Streak white. H. 2 to 2-5. S.G. 1-75. 



Comp. Am M + 41168 or Am S V Al S + 



24H= ammonia 5-7, alumina 11-4, sulphuric 

 acid 35-3, Avater 47-6 = 100-0. 



Localities. Tschermig, in Bohemia,. in the 

 Brown Coal formation. The crater of 

 Etna. 



TscHEWKiNiTE, Nicol, G. Rose. Massive 

 or amorphous. Colour velvet-black. Nearly 

 opaque. Lustre vitreous. Streak dark brown. 

 H. 5-5. S.G. 4-5 to 4-56. 

 Analysis, by H. Rose : 



Silica ..... 21-04 

 Titanic acid .... 20-17 



Lime 3-50 



Magnesia .... 0-22 

 Protoxide of manganese . 0-83 

 Protoxide of iron . . 11-21 



Peroxide of cerium, lantha- 



nium, and didymium . 47-29 

 Potash and soda . . .0-12 



104-38 

 BB intumesces much, becomes porous, 



and often incandesces ; in the strongest heat 



fuses to a black glass. 



Gelatinises readily in warm muriatic acid. 

 Locality. Near Miask, in the Ilmen. 



Mountains of Siberia, in granite. 



TURNERITE. 389 



Name. In honour of General Tschewkia, 

 Chief of the Russian Mining Corps. 



Brit. Mus., Case 38. 



TuESlTE, Thomson, Greg ^ Lettsom. A 

 mineral closely allied to Halloysite, Kaolin 

 and Lithomarge. Amorphous. Colour bluish 

 or milk-white. Opaque. Lustre resinous. 

 Sectile. H. 2-3. S.G. 2-5. 



Analysis, by Thomson : 



Silica 44-3 



Alumina .... 40-4 

 Iron, magnesia, and lime . 1*5 

 Water 13-5 



93-7 



BB becomes light blue and brittle : v/ith 

 soda fuses to an opaque mass. 



Locality. The banks of the Tweed, in 

 New Red Sandstone. 



Name. From Tuesa, the Latin name for 

 the River Tweed. 



Tuesite makes excellent slate-pencils. 



Tufa. See Calcareous Tufa; also 

 Travertine, Osteocoixa. 



TUNGSTATE OF CoppER is Said bv Dr. 

 Genth to occur in large crystals at Cosby's 

 mine, Cabarras co., N. Carolina. 



TuNGSTATE OF Iron, Phillips. See Wol- 

 fram. 



TuNGSTATE OF Lead, Phillips. See 



SCHEELETINE. 



TuNGSTATE OF LiME, Phillips. See 



SCHEELITE. 



TuNGSTEiN Blanc. See Scheelite. 



Tungsten, Scheele, Allan, Jameson. See 

 Wolfram. 



Tungsten Ochre, "^ 

 Nicol. { See WoLFRASi- 



TijNGSTic Ochre, f ine. 

 B. Silliman. J 



Turgite, Hermann. A reddish-brown 

 mineral (possibly a Red Hematite) from 

 the Turginsk Copper Mines in the Ural, and 

 the Altai. Its composition may be repre- 

 sented by the formula Fe2H = peroxide of 

 iron 94-7, water 15-3 = 100. S.G. 3-54 to 

 3-74. 



Name. After the River Turga, in the 

 Ural, because it is found in the copper mines 

 of that district. 



TtJRKis, V. Leonhard. See Turquois. 



TuRMALiN, Werner. See Tourma- 

 line, 



Turnerite, Levy, Dana. A mineral con- 

 taining alumina, lime, magnesia and a little 

 iron. Colour yellow or brown. Transparent 

 CO 3 



