474 T. W. E. DAVID, W. F. SMEETH, AND J. A, SCHOFIELD. 
(Plate 14, fig. 1), The sanidines are apparently all tabular ih 
form, some slices showing nothing but tabular sections while 
others yield only lath-shaped ones. . 
The ferro-magnesian constituent is represented by an egirine — 
which is present in considerable quantity (probably nearly 25/ 
of the whole bulk), It exhibits brownish-green to bluish-green — 
pleochroism with a small extinction angle. It is uniformly dis — 
tributed in minute angular patches moulded on the felspars with 
here and there a tendency to an elongated prismatic habit. In — 
places it shows ophitic structure on a small scale. The only 
porphyritic constituents are a few rounded grains of this same 
eegirine and a few large grains of magnetite. 
As accessory constituents there are a number of minute flakes 
of a brown biotite, some needles of apatite included in the felspars, 
a few zircons and a little magnetite. q 
Glassy Augite Andesite (1) No. 11. 
Greyish-black in the mass and has the appearance of a fine — 
grained andesite or basalt. a 
There are but few porphyritic constituents. Some corroded 
fragments of felspar, apparently monoclinic, and some grains ofa 
pale augite with faint pleochroism—yellowish- to pinkish-brow a 
There are one or two patches of magnetite (opacite) granules with 6 
traces of brown hornblendic material remaining. 
Next to these in point of size we have a sparsely scattered “ ‘ 
of small lath-shaped felspars, the majority of which are silt | 
twinned, but a few show lamellar twinning and appear to be 
oligoclase, The base appears to be glassy, but is generally 0 
quite isotropic and gives the impression of being in @ near, 
strain. It is quite colourless and in many places indefinite plates” 
of felspar material seem to have partially developed. 
This base is filled with very minute augite crystals. They 3 
for the most part well formed crystals, with short prismatic 8°” 
pale green in colour, and appear to have a small angle ofextinctio® — | 
