OF LITTLE K^fOTT (CTJilBERLAXD). 513 



No. II. Slightly more compact than the last described, with a 

 sharper and smoother fracture. Under the microscope, the hornblende 

 is seen to be slightly less abundant, rather more regular in external 

 form and less frequently interrupted by enclosures. These, as 

 well as some patches in the body of the slide, are occuj^ied by a pale 

 green viridite and irregular granules of a colourless mineral which 

 may be dolomite. Pelspar like that in the former slide, but rather 

 more abundant, and accessory minerals occur as before. 



iSTo. III. (Haifa yard from last specimen.) A mottled dark green 

 and pale pinkish grey rock, looking slightly coarser than the last. 

 Under the microscope the difference is not very material, except that 

 there is more felspar, this now being the dominant mineral. The 

 felspar is a little better preserved, and appears to be mainly plagio- 

 clastic. The extinction-angles are rather small, as if it were one of 

 the varieties rich in silica. There is also a fair amount of quartz 

 scattered about the slide. The rock, in short, is an ordinary diorite 

 of fairly characteristic ophitic structure. 



1^0. lY. Hornblende crystals, about -3 in. in diameter, abundant ; 

 very rough fracture. Except for the greater size of many of the 

 hornblende crystals and the decided predominance of that mineral, 

 the description of i^o. I. will apply. The bastite-like mineral occurs 

 associated with a granular, colourless mineral, probably of secondary 

 origin, which I cannot name. 



^0. V. A stiU coarser rock than the last ; hornblende crystals 

 sometimes fully -5 inch across and more conspicuously interrupted, 

 Making allowance for this, the microscopic structure is not materially 

 different from that of the last-named specimen. The sudden transi- 

 tion in the same crystal from the very dark brown to the almost 

 colourless and rather fibrous hornblende happens to be particularly 

 well exhibited (Plate XYI. fig. 2). There is also rather more calcite 

 in this slide than in the others. 



The isolated outcrop, mentioned above as probably connected with 

 the main mass of picrite, is a greyish rock containing, in a rather com- 

 pact base, small scattered whitish crystals. Under the microscope, 

 it is seen to be holocrystalline, consisting mainly of very decomposed 

 felspar, from which all distinctive characters have disappeared, and a 

 much altered hornblende, now to a large extent replaced by an earthy- 

 looking material almost opaque to transmitted light, and appearing 

 of a pale grey colour with reflected light, something like leucoxene. 

 There are some scattered granules of quartz, grains of iron peroxide, 

 possibly ilmenite, some calcite, and a good many belonites of a nearly 

 colourless mineral, which is frequent in diabases, and I think is some- 

 times described as apatite. 



A specimen of the altered Skiddaw Slate, taken from about one 

 foot distant from a junction with rock like "No. I., is a hard compact 

 brownish grey rock. Under the microscope it is seen to consist of very 

 minute and ill-defined granules of quartz, associated with an abun- 

 dant, colourless, fibrous, micaceous mineral, and with earthy granules. 

 There is a fair amount of a brownish fibrous mica ; ferrite, micaceous 

 minerals, &c., are sometimes aggregated in clustered patches, as 



2o2 



