ISriGKEL MINF.BALS PKOM: NEAV CALEDONIA, 77 



The above results do not aftorcl A'ery satisfactory data for a 

 formula, but approximately the mineral may be regarded as 



(NiO,MgO),„ (SiO,)8 + 3H3O or ^^] ,„Si«0,6 + 3H.,0, or, as 



mineralogically written, (MgNijioSig + 3H. 



I find that by far the major part of the nickel ore as shipped 

 to Sydney, consists of another hydrated silicate of nickel and 

 magnesia ; which is at once distinguished from the first by its 

 much darker apple-green colour, and by the differences in its 

 other physical properties for which I have proposed the 

 name oi^ — 



NOTTMEITE. 



This mineral also occurs in narrow veins and fissures in the 

 serpentine, but unlike the other it is not so much fissured itself, 

 nor is it permeated by thin plates of silica. It is amorphous, and 

 sometimes occurs in small mammillations — occasionally these 

 mammillations are covered with a layer of minute crystals of 

 quartz, which gives the mineral a beautiful frosted appearance. 



In colour it is a full apple-green. 



It does not fall to pieces when immersed in w^ater, neither does 

 it adhere to the tongue. 



To the touch it is slightly greasy, and may be readily polished 

 by scraping it with the thumb-nail. 



Its streak is shinv, and yields a pale green powder. 



Hardness, 20 to 2o. Sp. gr., 2-58. 



The specific gravity was taken from small fragments, sifted free 

 from all fine powder ; these were placed in the specific gravity 

 bottle, weighed, covered with distilled water and allowed to stand 

 for forty-eight hours, wdth occasional shakings so as to expel all 

 air bubbles ; after that time the bottle was filled up to mark, and 

 the operation finished in the ordinary way. "Without these pre- 

 cautions it is exceedingly difficult to rid the specimens of all air. 



Heated in a closed tube it gives oft* water and becomes grey. 

 Before the blo^vpipe it yields the usual nickel reactions. 



Like the former variety, it is dissolved by hydrochloric acid, 

 with the liberation of non-gelatinous silica. 



As will be seen from the accompanying results, the chemical 

 composition is by no means very uniform in different specimens: — 





I. 



II. 



III. 



Silica 



.. 58-763 



47-90 



49-54 



Alumina and iron ox. . , 



•509 



3-00 



1-60 



Nickel oxide 



undet. 



2400 



26-80 



Magnesia 



)j 



12-51 



13-86 



Lime 



traces 



traces 



traces 



Water 



8-038 



12-73 



nndet. 



10014 



