^86 PROCEEDINGS OP SECTION C. 



patclies. These are probably tabular felspars. Here and there 

 are brick red fragments inclining to vermilion in places. They 

 are evidently fragments of lava which owe their red colour to 

 some secondary chemical action. The lai-ge black grains are 

 titaniferous iron. The smaller dark grains are magnetite, nearly 

 colourless grains of various shades of grey also occur : all the 

 fragments are more or less rounded, and many of them as round 

 as shot. 



In Slide No. 2a there are deep grass-green translucent grains, 

 and one of a bright bluish-green tint, which may be carbonate of 

 copper. There is a great deal of epidote and chlorite. Several 

 large greenish-grey grains are very rich in magnetic iron. 



Two species of felspar are observable in one of the greyish- 

 purple trachyte lavas. One shows in stout stunted tabular forms, 

 and is much kaolinised, the other occurs in slender lath-shaped 

 prisms and is semi-translucent. 



In Slide No, 3b is a microscopic vein of metallic copper travers- 

 ing a pale greenish-grey mineral. A micro-porphyritic crystal of 

 felspar occurs in one of the fragments of decomposed basalt. A 

 bright bluish-green mineral in the same slide is perhaps copper 

 carbonate. 



In Slide No. 2c from Holt-Sutherland, is one undoubted frag- 

 ment of deep bottle-green hornblende, showing characteristic 

 cleavage and strong dichroism. 



One class of fragments is a lava of a transparent pale greenish- 

 grey, witli patches of yellowish-green, and dotted all over with 

 opaque ragged crystals of ilmenite. Slender prisms of turbid 

 felspar are just recognisable in the ground-mass, and acicular 

 radiating crystals of actinoiite or epidote strongly pleochroic, occur 

 as secondary inclusions in the greenish patches. The fragments 

 of this lava appear to be enormously i^ich in ilmenite. 



Another specimen similar to the above consists of a holocrystal- 

 line base of felted felspar, with pale greenish-grey interstitial 

 material and abundant ilmenite in small aggregates with ragged 

 edges. A micro-porphyritic multiple-twinned felspar is enclosed 

 in this ground-mass. Hornblende is present in green transparent 

 grains, shewing the characteristic prismatic cleavage. The original 

 • outlines of the crystal have been completely obliterated by friction. 

 One of these yellowish-green grains shows faint traces of an 

 original augite cleavage, but the hornblende cleavage predominates, 

 so that it is probably uralite. Some of tlie lapilli of lava are very 

 sharp and angular, composed of an intensely black ground-mass, 

 in which are enclosed lath-shaped felspars and small yellowish- 

 green patches, one of the larger ones looking like a pseudomorph 

 after olivine. Black opaque patches are very frequent. The 



