found at Makariwa, near Invercargill, New Zealand. 59 



Troilite. — Rather small, yellow, and bronze-coloured metallic 

 specks observable in the sections in reflected light belong, no doubt, 

 to this mineral, but they are very scarce, and the aggregate per- 

 centage indicated by them, as present in the stone, would be very 

 small indeed. According to the quantity of sulphur obtained in a 

 preliminary chemical examination by Mr. James Allen, a former 

 student of the Royal College of Science, London, the stone should, 

 however, contain an appreciable percentage of troilite ; and it is, 

 therefore, very probable that some of the black grains, without 

 metallic lustre, observable in the sections, belong to it, being partly 

 oxidised and coated over by hydrous ferric oxide. Dark dull spots 

 on the surfaces of many particles of the nickel-iron, or closely joined 

 therewith, are very likely also due to this process. 



Magnetite. — The majority of the rather abundant dark grains, some 

 of which show square, others hexagonal, outlines, belong doubtless to 

 this mineral. The distribution of the grains is very irregular; in 

 some parts they are abundant, in others rather scarce ; their closest 

 aggregation is generally in the borders they form around chondri of 

 olivine. Chromite may also be present, but only in very small 

 quantity, as the chemical examination of the stone afforded only a 

 trace of chromium. 



Specific Gravity. 



The specific gravity of the stone, determined from several small 

 fragments, varied between 3'31 and 3'54 : the variation is, no doubt, 

 due to the unequal distribution of the metallic particles. 



Results of the Chemical Examination of the Stone. 



A chemical examination has since been undertaken by Mr. L. 

 Fletcher, of the Mineral Department, British Museum. The 

 examination is not yet finished, but the results already obtained by 

 him indicate that the percentage mineral composition is approximately 

 expressed by the following numbers : — nickel-iron, 1 ; oxides of nickel 

 and iron, 10 ; • troilite, 6 ; enstatite, 39 ; olivine, 44 The details of 

 the examination will be communicated later. 



Description of the Figures. 



All the figures are drawn in ordinary light from thin slides cut in 

 different directions from one of the fragments of the stone.* The 

 nickel-iron particles, as seen in reflected light, are indicated by 



* The small pieces remaining after the slicing wpre used for my preliminary 

 chemical examination and the determination of the specific gravity. 



