390 TURQUOIS. 



to translucent. Lustre adamantine. Streak 



white or greyish. H. above 4. 



Fiff. 443. 



LocaTdy. France, at Mount Sorel, in 

 Dauphiny. 



Name. Named by Levy after Mr. Turner, 

 in whose collection it was first noticed. 



TuRQUOis, Dana, or TuKQUOisE. There 

 are two varieties of Turquois, the Oriental 

 or Mineral Turquois (Turquois de vinlle 

 rocJie), and the Occidental or Bone-Turquois 

 (Odontolite : Turquois de nouvelle roche). 



The first, or true Turquois, occurs reniform, 

 stalactitic or incrusting. Colour a peculiar 

 bluish-green. Feebly translucent to opaque. 

 Lustre somewhat waxy, internally dull. 

 Streak white. Cleavage none. Fracture 

 sraall-conchoidal. H. 6. S.G-. 2-6 to 2-83. 



Co7np. Diphosphate of alumina, or M^ 



F + 5H (coloured by oxide of copper) = 



alumina 46"9, phosphoric acid 32-6, water 



20-5 = 100. 



Analysis of blue Oriental Turquois, by 



Hermann : 



Alumina . . , . 47-45 

 Phosphoric acid . . . 27-34 

 Oxide of copper . . . 2*02 

 Peroxide of iron . . . I'lO 

 Peroxide of manganese . 0-50 

 Phosphate of lime . . 3-4i 

 Water 18-18 



10000 



Berzelius obtained, by analysis, phos- 

 phate of alumina, phosphate of lime, silica, 

 oxide of iron and copper. 



In matrass decrepitates violently, and 

 gives olf water. BB in the reducing flame 

 becomes brown, and colours it green, but is 

 infusible; with borax or salt of phosphorus 

 fuses readily to a transparent glass, which 

 on cooling is faint copper-green in the 

 outer flame, aud cloudy-red in the inner, 

 especially if tin be addea. 



Soluble in muriatic acid without elTer- 

 vescence: the solution alFords a fine blue 

 colour with ammonia, which is not the case 

 with Odontolite. It may also be distin- 

 guished from Odontolite by its perfectly 

 even and uniform texture, by its specific 

 gravity, and by not eftervescing with acids. 



Odontolite is found with fossil bones and 

 teeth (on which account it was called by 



TURQUOIS. 



the ancients £A£<p«? o^vxtc?^, and appears to 

 be bone or ivory coloured by phosphate of 

 iron. It is of a sky-blue colour, passing 

 into greenish-blue and apple-green ; fre- 

 quently with black dendritical markings, 

 which greatly impair its beauty and value. 

 Its texture, which is very compact and 

 earthy, exhibits traces of animal structure, 

 in slender fibres of a lighter tinge than the 

 rest of the mass, either parallel with or 

 crossing each other, so as to present a sort of 

 net-work, according as the section has been 

 made parallel with or at right angles to the 

 tusk. 



The distinction is made in commerce 

 between Turquois and Odontolite ; the terms 

 oriental and occidental being employed by 

 jewellers rather to distinguish the finer from 

 inferior stones, than to denote any differ- 

 ence either of chemical composition, or of 

 country. {3Iawe.) 



In the " Oriental accounts of the Pre- 

 cious Minerals, " by Prinsep, it is stated, 

 that " the Abu-Is'haqi (father of Isaac), or 

 genuine turquois, is the produce of the 

 mines of Ajisar, near Nishapur^ in Khorasan 

 (the same place mentioned as 3Iichebourg, 

 in Taverniei-'s Travels in India). All autho- 

 rities concur that these are the only tur- 

 quois mines in the world : the stones are 

 said to vary from pale blue to green and 

 white, but all except the azure are worthless. 

 A curious fact is mentioned, also, which, 

 from the nature of the mineral may readily 

 be believed, though it has not been observed 

 in Europe : the real blue turquois of Ni- 

 shapiir changes in colour when kept near 

 musk or camphor, also from the dampness 

 of the ground, as well as from exp(isure to 

 the fire (Pliny also remarks of the Callais 

 ' qu£e sunt earum pulchriores, oleo, unguento, 

 et mero colorem deperdunt ') ; the inferior 

 stones become discoloured even without 

 this test 'by gradual decomposition or 

 efflorescence.'* The Khawas-ul hejar makes 

 the clearness or dulness of the Turquois 

 vary according to the atmospheric changes. 

 ' It brightens the eyes ; is a remedy for 

 ophthalmia, and bites of venomous animals ; 

 it is used in enamelling sword handles,' &c. 

 'The Badakshani Turquois essentially dif- 

 fers from the Nishapuri, in being able to 

 withstand the heat of a fire for ten days 



* When the Oriental Turquois becomes disco- 

 loured, it is only necess:iry to pass it over the mill, 

 so as to remove the external surface, 'o restore 

 its former appearance and colour. Odontolite 

 when discoloured by time may be revived by im- 

 mprsion in a solution of oxide of copper, but the 

 effect only lasts for a few^ days. 



