328 ME. ALEEED HAEKEE ON THE [May 1 896, 



EXPLANATION OF PLATES XIII. & XIY. 



[The numbers in brackets are those of the figured slides in the collection of the 

 Geological Survey at the Jermyn Street Museum.] 



Plate XIII. 



Fig. 1. [6704.] X20. Granophyre showing native and foreign augites. To 

 the right of the magnetite in the centre are several granules of 

 augite proper to the granophyre : to the left of the figure is a 

 gabbro-xenolith but little altered. In this the pale, well-cleaved 

 augite forms ophitic plates enclosing the felspar, and the only 

 alteration is a little marginal conversion into hornblende. The 

 basal striation is not seen here. See p. 324. 



Fig. 2. [6705.] X40. Granophyre showing xenocrysts of augite derived from 

 gabbro. This is proved by their retaining the basal striation and 

 schillerization, which is combined with the ordinary orthopinac- 

 oidal twinning to give the ' herring-bone ' structure. See p. 324. 



Fig. 3. [6709.] X 20. Similar augite-xenocrysts converted into hornblende, but 

 still retaining the basal schillerization. See p. 324. 



Fig. 4. [6705.] Xl50. Granophyre showing native hornblende. This is 

 proved by its ei*ystal-form. See p. 324. 



Fig. 5. [6708.] X150. Also showing idiomorphic hornblende, and, in addi- 

 tion, actinolitic needles embedded in clear quartz. See p. 326. 



Fig. 6. [6705.] X20. Eing of hornblende-crystals surrounding an area 

 of clear quartz, to which they present idiomorphic outlines. 

 See p. 326. 



Plate XIV. 



Fig. 7. [2674.] X 20 ; polarized light, crossed nicols. Granophyre containing 

 a xenocryst of enstatite, probably derived from gabbro. The 

 interior of the crystal is converted into the usual serpentinous 

 pseudomorph, but the margin is replaced by fibrous hornblende. 

 Towards its right-hand end the crystal encloses two or three patches 

 of compact hornblende, probably an original intergrowth. See 

 p. 325. 



Fig. 8. [6707.] X20; polarized light, crossed nicols. Granophyre with druse, 

 occupied by quartz and calcite ; a feature common to the ordinary 

 coarse granophyres of the district. See p. 326. 



Fig. 9. [6707.] X20 ; polarized light, crossed nicols. Granophyre showing 

 delicate micrographic intergrowtbs of felspar and quartz. This also 

 is characteristic of the ordinary granophyres of the district, from 

 which the rocks described (when not showing actual relics of foreign 

 material) differ only in their greater richness in the coloured 

 minerals. 



Fig. 10. [6709.] X20; polarized light, crossed nicols. An angular patch rich 

 in hornblende and magnetite, probably an altered xenolith of 

 basalt. See p. 326. 



Fig. 11. [6701.] X20 ; outlines drawn by polarized light, crossed nicols. Fine- 

 textured variety of granophyre (but non-granophyric), containing 

 various xenoliths. In the lower part of the figure are fragments of 

 altered glassy basalt ; above and to the right is a piece of quartzose 

 grit, and to the left of this a felspar-xenocryst. See p. 326. 



Fig. 12. [6702.] XlO. Another fine-textured example, showing flow-structure. 

 There are numerous xenoliths, chiefly of basalt, the smaller ones- 

 lenticular in form and arranged along the stream-lines. See 

 p. 326. 



