49 TranHictions. 



Black Island, 10. — Black basaltic rock, with olivine freely developed, 

 Groundmass liolocrystalline, consists of latli-shaped feldspars, brown augite, 

 olivine, magnetite, and splienc. Feldspar also occurs in larger form, with 

 rounded outline, and showing between crossed nicols a few very narrow 

 bands widely spaced. ' Olivine inclusions in this feldspar. A few^ larger 

 forms of pale-brown augite with rounded outline. Frequent larger olivines, 

 mainly idiomorphic, but some with corroded outhne. Trachydolerite. 



Black Island, 11. — Weathered pebble. Rough-textured fine diorite in 

 structure. Colour brow^nish-grey. Large plates of augite, in parts markedly 

 diallagic. The more normal mineral has a distinct pleochroism from pale 

 bluish-grey to pale pink. Here and there is slight decomposition, with 

 development of serpentine. There is a very little brown mica, with strong 

 pleochroism. Between the augite areas is a matwork of clear feldspars 

 in moderately stout forms, apparently labradorite. Slight decomposition 

 occurs here and there. Ilmenite and apatite are also present. Augite- 

 diorite. 



Black Island, 12. — Very light warm buff, with greener shades locally. 

 Trachytic texture. Ill-bounded feldspars, mainly lath-shaped, b\it some 

 of stouter section, in a groundmass of minute feldspar mosaic. A fair 

 (|uantity of aegirine-augite, pleochroism yellow-brown-green to blue-olive- 

 green, in small prismatic forms and grains, for the more part ill-bounded. 

 Possibly a little apatite. Under the |^-inch objective minute hexagonal 

 and square forms of a clear mineral are visible. When the section is treated 

 with hydrochloric acid, well washed, and stained with fuchsin it takes the 

 dye locally where these hexagons and squares occur, and shows them marked 

 out by the cleavage-cracks in larger forms of a mineral which is almost 

 certainly nepheline. Phonolitic trachyte. From south-west corner of 

 island ; occurs /« situ. This is 610 of official report, but there reported 

 in error as from south-east of island. 



Black Island, 13. — Volcanic agglomerate. Greenish base with black 

 nodules, evidently basaltic. From north end of island. Described on 

 page 139 of official report. 



Black Island, 14. — Dark-grey rock, almost black. Tendency to con- 

 choidal cleavage. Very close grain. Micro-crystalline (juartz and reddish- 

 brown mica are the prominent constituents. There is a distinctly parallel 

 structure throughout the slide, but no banding. A fair amount of magnetite 

 in irregular patches. An altered sedimentary rock fiom a contact zone. 

 Apparently official specimen 525, page 135. 



Black Island, 15. — Very dark-grey compact rock. Possibly a very little 

 olivine. Groundmass microlitic. Consists of feldspar laths all conforming 

 to one general direction, sphene. magnetite, and augite. In this occur 

 larger water-clear feldspars, some striated, some zoned, many in associated 

 intergrown crystals. A feAV porphyritic very pale-brown augites, and 

 sphene in larger forms than in the goieral ground. From top of north 

 peak of island, practically in situ. 



Black Island, 16.- — Slaggy vesicular lava, exterior with green tints, 

 fracture red and black. Very closely resembles Brown Ishnid, 4. From 

 top of north peak of island, in situ. 



Browx Island. 



Broini Island, !.■ — A very pale-grey slightly greenish trachyte. Com- 

 pact and hard, weathered surface hard filso. A few dark acicular crystals 



