254 



greenish-yellow and rose kunzites (triphane) from Maharitra on 

 j^ffyJai/ascar ; tlie lilac and rose kunzites of Ampasihiatra are irn- 

 l)oddcd in a kind of kaoline-earth, generated from the spodiunene 

 by decaying-processes. The green kunzites possess the greatest values 

 of their refractive indices, however only little differing from the 

 other ones, whi-le the rose tinged crystals have a smaller, the colour- 

 less ones yet smaller values for those constants. 



We found by means of the immersion-method n^ = 1,658 and 

 11^ =: 1,673, which values do not differ appreciably from the mean 

 values: ^1 = 1,6588, n^ = 1,6645 and n^ = 1,6750. M For the ana- 

 lysis of the red and greenish crystals, the following data are given 

 in literature; they are j-eproduced here for comparison with the 

 composition of the Californian kunzite : 



rose cristals: \ green cristals: 



Si02 : 63,85% CaO : 0,52o/„ MnO : trace 



AI2OS : 29,87o/o NazO 0,98 "0 FeMj : 0, 1 50/0 



LhO : 3,16^Iq MgO : 0,13" io KoO :0,13"'o 



Residue: 0,37» q. 



SiOi : 62,2 1 "/o CaO : 0,50*^/0 MnO : trace 



^/aOg: 29,790/0 Na20: l,030/o ^^203:2,480/0 



LLO : 4,02'/,, MgO : trace KnO :0,21o/o 



Residue: 0,25o/o. 



From tliese data resiUts, that the quantity of SiO^_ in the rose 

 crystals is about the same as for the pale rose kunzite of Rincon; 

 but the content of Al^O^ is much greater in the mineral of Mada- 

 (jascar, and thus the Li^O appreciably less than in the American 

 kujizite. The sum of those three constituents does not differ very 

 much in all these cases: 97,5 "/^ for the kunzite of Madagascar, 

 98,2 7o lor that from Rincon. The specific gravity of the rose species 

 is about 3,177; — a value, only slightly different from the value, 

 determined by us: f/40 = 3,3()l +0,005, at 25°, 1 C. 



The refractive indices of the melted, feebly birefringent product, 

 were found to be «1 = 1,518 and n.^-=\,t)%); the birefringence is 

 not greater than 0,002. 



At 25°,1 C. the specific gravity of the melted and solidified sub- 

 stance was determined : di° = 2,373, when the preparation was heated 

 dnring several hours at a constant temperatni-e, just below the 

 meltingpoint; under the microscope the obtained product then showed 

 the typical aspect of the aggregates of scales, which ai-e always found 

 with the /?-spodumene ; they have a weak birefringence, and an 

 irregular, often undulatory extinction. When rc-spodumene was not 

 melted before, but onl} kept at a constant temperature below the 

 meltingpoint, the snbstance appeared to be wholly transformed into 

 the same /?-modification, with a specific gravity of: c/^o = 2,376 at 



1) DuPARc, WuNDER ct Sabot, Mém. de la Soc. physique de Geneve, 36, 402, 

 (1910;. 



