TOURMALINE. 

 I. Magnesia Tourmaline. Comp. ll^ Si 



+ 3fi Si + iJ Si, or (K^ ^ ji") si. S.G. 3 to 

 3-07 ; Biean 3'05. 



Analyses, bv Eammehberg. (a) Brown, 

 from W. Kappel, Carinthia. S.G. 3-049. 

 (b) Black, from Zillerthal. S.G. 3-054. 

 (a) (fe) 



Loss by ignition 



Silica 



Alumina . 



Eoracic acid 



Peroxide of iron 



Protoxide of iron 



Magnesia 



Lime 



Soda 



Potash 



Phosphoric acid 



Fluorine . 



103-19 103-54 



IL Iron-magnesia Tovrmaline. S.G. 3-05 

 to 3-2 ; mean 3-11. Black, from Greenland. 

 S.G. 3-072. 



Silica . 



Alumina 



Eoracic acid . 



Peroxide of iron 



Protoxide of iron 



Magnesia 



3-19 



3-54 



38-85 



37-94 



31-32 



33-64 



8-25 



8-58 



1-27 



2-79 







0-37 



14-89 



10-46 



1-60 



0-98 



1-28 



2-13 



26 



0-37 







0-24 



228 



2-50 



Lime 

 Soda . 

 Potash . , 

 Phosphoric acid 



IIT. Iron Tourmaline. 

 Black, from Bovey Tracey 



Silica . 

 Alumina 

 Eoracic acid 

 Peroxide of iron 

 Protoxide of iron 

 Magnesia 

 Lime . 

 Soda . 

 Potash. 

 Phosphoric acid 



. 37-70 

 . 34-43 

 . 7-36 

 . 4-63 

 . 0-25 

 . 9-51 

 . 1-25 

 . 2-00 

 . 0-43 

 . 0-11 



97-67 



G. 2-94 to 3-11. 

 S.G. 3-205. 



. 37-00 



. 33-09 



. 7-b6 



. 9-33 



. 6-19 



. 2-58 



. 0-50 



. 1-39 



. 0-65 



. 0-12 



98-51 



Silica . . . . 



Alumina 



Boracic acid . 



Peroxide of iron . 



Protoxide of iron . 



Protoxide of manganese 



Magnesia 



Lime . . . . 



Soda . . . . 



Potash . . . . 



Phosphoric acid . 



IV. Iron - manganese - lithia Tourmaline. 

 S.G. 2-94 to 3-li. (a) Bluish-black, from 

 Sarapulsk, in the Ural. ^ S.G. 3-164. (6) 

 Green, from Elba. S.G. 3-112. 



TOURMALINE. 



(a) 

 . 38-30 

 . 36-17 

 6-32 

 6-35 

 3-84 

 3 71 

 0-53 

 0-27 

 3-37 

 0-33 

 0-06 



99-25 



('0 

 38-1^ 

 39-16 

 7-10 

 3-14 

 4-74 



1-00 

 0-84 

 2-40 

 0-34 

 Lithia, 0-74 



97-65 



V. Lifhia Tourmaline. S.G. 3 to 3-1. 



Bed, from Schaitansk 

 3-082. 



Silica . 



Alumina 



Eoracic acid . 



Protoxide of man. 



Magnesia 



Lime . 



Soda 



Potash . 



Lithia . 



Phosphoric acid 



in the Ural. S.G. 



38-38 

 43-97 

 7-41 

 2-60 

 1-60 

 0-62 

 1-97 

 0-21 

 0-48 

 0-27 



97-51 



Brit. Mus., Case 40. 



M. P. G. Horse-shoe Case, ISTos. 866 

 to 881. 



The colours of the Tourmaline are gene- 

 rally dull, and so dark as to appear nearly 

 black. It varies, too, very much in trans- 

 parency, and consequently the stones which 

 possess that quality in the highest degree 

 are the best adapted for the use of the 

 jeweller. On account of its deficiency of 

 lustre, and its smoky or muddy tint, it is 

 not held in any great estimation as a gem ; 

 nevertheless, when well selected, cut thin, 

 and set with a proper foil, it possesses con- 

 siderable beauty. Though classed amongst 

 the least valuable of the precious' stones in 

 Europe, it is highly prized in Brazil, where 

 it is worn in rings, chiefly by dignitaries of 

 the church. 



The Red Tourmaline, or Bubellite, also 

 constitutes a fine stone when it is free from 

 flaws. The finest known specimen of this 

 gem is in the collection of minerals in the 

 British Museum, Room III, Case 40. It is 

 of uncommon form and dimensions, and was 

 presented to Colonel Symes by the king of 

 Ava, when on an embassy to that country. 

 It has been valued at £1000 sterling. 



This variety comes from Siberia, Ava, 

 and Ceylon. The yellowish -grey and hya-' 

 cc 



