Yol. 52.] NICKEL-BEARING SERPENTINE. 455 



Si0 2 41-81 



A1 2 3 068 



As 2 3 013 



Fe 2 3 5-55 



FeO 1-42 



CuO 0-15 



NiO 492 



CaO trace 



MgO 39-86 



Combined water 490 



Moisture 0*04 



99-46 



The chemical analysis of the rock indicates that quite half the 

 minerals must be anhydrous, so one at least of these — olivine,, 

 enstatite, augite, or hornblende — ought to be present. There is a 

 group of augites and hornblendes in which the amount of lime is 

 very small, but they generally are either altered and contain a 

 large percentage of water, or are rich in iron and soda. The amount 

 of iron found in this rock is, however, not much more than sufficient 

 for the magnetite and awaruite. Anthophyllite is rich in magnesia 

 with some ferrous oxide, but is rhombic, and most, if not all, of 

 the pyroxenic mineral in this rock is monoclinic. But the analysis 

 shows almost 5 % °f nickel oxide, while the awaruite observed 

 would not require so much as 1 °/ . Thus the nickel oxide must be 

 largely present in one of the transparent minerals, and, since lime 

 is only present as a trace, we infer that the anhydrous mineral is a 

 variety of pyroxene in which lime has been replaced by oxide of 

 nickel. 1 



In the hope of obtaining further proof, the rock was coarsely 

 ground up in a mortar, and an attempt made to separate the light- 

 coloured fragments from the darker. To obtain the former clean 

 was comparatively easy, but the dark were generally encrusted with 

 the lighter. The specific gravity was determined : that of the rock 

 itself was 2-71 : of the light fragments 2*68, and of the dark 3*17 

 (lower than one would expect, owing to their not being clean). The 

 light portion of the rock was analysed and found to contain nickel, 

 which again points to the presence of nickel in the pyroxenic mineral. 



A third specimen was examined which also had been obtained 

 from the summit of the Eiffelhorn, at a short distance from the 

 other two. Under the microscope it was rather less augitic than 

 the last named, but that mineral certainly was present, though no 

 lime (after using the test described above) was found 2 ; nickel also 

 was sought for and was not found. As the slice shows a grain or 

 two of awaruite, this metal is probably present only sporadically, 

 and not as a constituent of the pyroxene. 



1 [Mr. F. Kutley, since this paper was read, has kindly called my attention 

 to a description of hydrous nickel silicates (garnierite and noumeaite) by Prof. 

 Liversedge (Journ. & Proc. Koy. Soc. N.S.W. vol. xiv. 1880, pp. 231 et seqq.). 

 Analyses of these and of nickel- magnesia silicates are given by Dana (' System 

 of Mineralogy,' 6th ed. 1892, pp. 676, 677, 686), but all seem to differ from the 

 above in important respects. — T. G. B.] 



2 The absence (virtual) of lime was oonfirmed by an independent analysis. 

 Q. J. G. S. No. 207. 2 1 



