THALLITE. 



When first noticed, this mineral, which is 

 identical with Saponite, was supposed to 

 contain a new metal, to which the name 

 Thalium was given. The earth of this 

 base was called Thalia, and the mineral 

 from which it was extracted Thalite. 



Locality. Between Pigeon Point and 

 Fond du Lac, on the north shore of Lake 

 Superior. 



Thallite, Karsten. (From SaXXu, to 

 grow green.^ Acicular crystals of Epidote, 

 met with in the Department of Isere, in 

 France ; at Bourg d'Oisans, in Dauphiny ; 

 the Alps, &c. Beaudant also applies the 

 name to the Epidote from Logrosan, on 

 the slope of the Sierra de Toledo, in Spain. 



Brit. Mus., Case 85. 



Tharandite, Kiihn. A greenish macled 

 variety of Pearl Spar, found at Tharand, in 

 Saxony» 



Fig. 430. 



Camp. Ca C + Mg C. 



Analysis, by Kiihn : 



Carbonate of lime . - 64-76 

 Carbonate of magnesia . 42"10 

 Carbonate of iron . . 4-19 



101-05 



Brit. Mus., Case 47. 



Thenardite, Casaseca, Dufrenoy, Nicol, 

 Phillips. Rhombic. Cleavage basal. Pri- 

 mary form a right rhombic prism. Occurs 

 in rhombic octahedrons, simple or modified 

 on the summit, aggregated in crusts and 

 druses. Colour white. Translucent, or pel- 

 lucid. Lustre vitreous. Effloresces and 

 becomes covered on the surface Avith a white 

 powder on exposure to the air. Taste saline. 

 Wholly soluble in distilled water. Refracts 

 doubly. H. 2-5. S.G. 2 6 to 2 -73. 



Comp, Anhydrous sulphate of soda, or 



Na S = soda 56-3, sulphuric acid 4'3-7 = 100. 

 Analysis, from Tarapaca, by Allan Dick : 

 t Sulphuric acid . . . 55-11 



Soda 42-37 



Insoluble . . . .219 



99-67 

 3B colours the flame deep yellow, fuses, 



and on charcoal is reduced to sulphide of 



sodium. 

 Localities. Les Salines d'Espartines, five 



THERMOPHYLLITE. 377 



leagues from Madrid, and 2h from Aranjuez, 

 In the winter, saline springs rise from the 

 bottom of a basin, and in the summer, when 

 the liquid has attained a certain degree of 

 concentration in consequence of the evapo- 

 ration, a portion of the salt, which was held 

 in solution, is deposited in more or less re- 

 gular crystals. 



Locality. Tarapaca, in Peru ; with Glau- 

 berite and Hayesine. 



Name. After L. J. Thenard, French 

 chemist. 



Brit. Mus., Case 52. 



Thenardite has been used by Mons. 

 Rodas in the manufacture of soap. 



Ther^ionatrite, Haidinger, Dana, Nicol. 

 Rhombic. Occurs in rectangular tables 

 with bevelled sides ; also as an efflorescence. 

 Colourless. Lustre vitreous. H. 1 to 1-5. 

 S.G. 1-5 to 1-6. 



Fig. 431. 



Comp. Hydrous carbonate of soda, or 



Na C+H = soda 50-0, carbonic acid 35-5, 



water 14-5 = 100. 



Analysis, from Debreczin, by Beiidant ; 

 Carbonate of soda . . . 73-6 

 Sulphate of soda . . . 10-4 

 Chloride of sodium, &c. . . 10-4 

 Water 13-8 



108-2 

 BB like Natron, but does not melt in its 

 water of crystallization. 



Localities. The Steppes between the 

 Ural and Altai Mountains. The Macarius 

 desert, in Lower Egypt. The natron lakes 

 at Lagunilla, in Colombia. The plains of 

 Debreczin, in Hungary. 



Thermophyllite, Nordenskiold. A mi- 

 neral resembling Chlorite, occurring in crys- 

 tals and grains in an amorphous base re- 

 sembling Steatite, which is probably amor- 

 phous lliermophyllite. Colour light brown 

 to silver-white. Lustre pearly. Fracture 

 uneven, except in the direction of the 

 cleavage. H. 1-5 to 2. S.G. 2-66. 



Comp. (R5R) bi+2H. 



Analysis, by Augustus B. Northcote : 

 Silica . . . ,, . 41-73 . 

 Alumina .... 5'52 

 Protoxide of iron . . 1-60 



