NICZEL-IEON ALLOY AWARUITE OF NEW ZEALAND. 631 



band corner of centre bar of cross is seen in convergent polarized light 

 a fine optic axis with p <: v. Above the cross-shaped grain, sepa- 

 rated from it by a narrow band of Olivine, there is another grain of 

 Enstatite showing a number of well-marked cleavage-cracks. In 

 several parts of the Olivine are seen in convergent polarized light fine 

 optic axes, and two light yellowish-green grains of it, near the centre 

 of the figure, adjoining the Enstatite, are indicated by a line and the 

 letter o. 



Fig. 2. In this the Olivine is, if anything, clearer and less cracked than in fig. 1. 

 There is only one grain of Enstatite shown in upper part of the figure, 

 recognizable by its numerous parallel cleavage-cracks, in the line of 

 which it extinguishes between crossed Nicols. The large irregularly- 

 contoured black grain and several far smaller black grains near it are 

 feebly brown, translucent, and consist either of Picotite or Chromite, 

 probably the former. 



Fig. 3. This shows two grains of Enstatite divided near centre of the figure by 

 fine-granular Olivine, full of minute black opaque and dark brown 

 translucent particles of either Picotite or Chromite. The largest grain of 

 Enstatite is very clear, and shows only a few cleavage-cracks ; at the 

 margin of the figure it becomes slightly dusky. The other grain of 

 Enstatite on the left shows both prismatic and brachy-pinacoidal 

 cleavage-cracks, and is therefore a basal section, disclosing in conver- 

 gent polarized light between crossed Mcols a pretty perfect interference- 

 figure ; at the upper end it is broken into by a grain of Olivine. The 

 green -coloured grain (o) below the last-noted Enstatite-grain is Olivine, 

 like those in fig. 1, characterized by a rough surface and the same 

 range of brilliant polarization-colours as the neighbouring colourless 

 Olivine. The two black opaque grains at bottom of the figure are 

 probably Chromite. 



Figs. 4, 5, & 6 are drawn in ordinary light from sections cut in different direc- 

 tions from a piece of medium-grained, though rather dull and com- 

 pact-looking Peridotite from the Red Hill. Magnified 20 diams. 



Fig. 4. In this are shown two grains of Enstatite, a large one in the upper 

 part, and a small triangular one at the lower margin. Both these 

 grains are more or less fibrous, and show streaks parallel to fibres 

 densely filled with a fine, dark dust, probably the commencement of 

 - serpentinization. The Olivine is in parts very clear and not much 

 cracked ; but in others it is slightly (on the right-hand edge of the 

 figure very densely) filled with fine, dark dust, as in the case of the En- 

 statite. The large black grain within the Olivine is quite opaque, and 

 probably consists of Chromite. 



Fig. 5. This shows on the left side a large grain of Enstatite, very clear and 

 with well-pronounced cleavage-cracks. On the right-hand edge there 

 is a smaller grain of this minex'al, also clear, showing faint cleavage- 

 cracks ; and across the middle a row of small, feebly brown, translucent 

 grains of probably Picotite. In the centre of the figure, and in contact 

 with the large grain of Enstatite, there are grains of light yellowish- 

 green Olivine, similarly characterized as the grains in figs. 1 & 3. The 

 Olivine (o, o) in the lower part of the figure is very clear, but that in 

 upper part is dusky and more fissured. The large irregularly-shaped 

 black grain is in parts faintly brown translucent, the small adjoining 

 one is quite opaque ; they probably consist respectively of Picotite and 

 Chromite, 



Fig. 6. This shows the grains of Enstatite, one on the lower right-hand edge, 

 the other on the left-hand edge. Both are rather fibrous, and in the 

 lower one a dusty streak (similar to those in fig. 4) runs in the line of 

 the fibres ; in the other grain such a streak runs across the fibres, and 

 there are also dusty patches and several strong dark irregular cracks. 

 The Olivine between these Enstatite grains is also in parts more or less 

 dimmed by dark dust. The black grains are opaque and probably 

 Chromite. 



