250 TATE: LAKE COUNTRY ROCKS. 
reflected light, note that the red colour of the hand specimen is due 
to the action of the iron-oxides upon the kaolinised felspars. 
Compare with slide 8. 
[4] Buttermere ‘syenite’: Scare Force, Cut from a flesh- 
colouredspecimen of medium granitic texture. A granular intergrowth 
of guartz and felspar, the latter Bonin as matrix and often 
penetrating the former. Quartz with sharp rectangular outlines 
impressed on the interstitial pellucid ae the latter extinguishing 
uniformly in patches over wide areas. Microperthite structure of 
felspar predominating. ‘Large patches have more or less the aspect 
of porphyritic constituents as if a considerable amount of felspar 
substance had first separated as distinct crystals and then the 
remainder of the felspar substance had intercrystallised with quartz 
to form the matrix’ (Teall). | Ferromagnesian component after 
hornblende plates is now in a chloritoid state giving feeble pleochroic 
effects. Iron oxides (hematite, magnetite, limonite) accompany 
the above secondary products. Examine by reflected light and 
compare with slide 
[4a] Granophyre (Rosenbusch) ENNERDALE. Slide cut from 
a sombre fine-grained specim A granophyric intergrowth 0 
guartz and felspar is here seu exhibited, the two minerals 
polarising in uniform tints over a greater part of the slide. A radial 
grouping is common with occasionally central strongly polarising 
grains. The ferromagnesian component is scattered uniformly 
throughout the slide in small crystals of green hornblende, a few of 
which are still fresh and strongly pleochroic, but for the most part 
represented by a chloritoid substance with but feeble action on 
polarised light; associated with this are a few specks of reddish- 
brown somewhat translucent z/menite, powdered over with silvery 
leucoxene (best observed by reflected light), and also by a few 
grains of magnetite. Apatite is plentiful, enclosed in the hornblende, 
' but elsewhere it is a little difficult of identification and needs to ae 
_ carefully sought for, Compare slide 4. oe 
[x6]. Porphyritic diabase: Eycorr Hitt. Plagioclase crystals 
(labradorite) in large tabular plates, showing Carlsbad and also 
albite twinning, frequently encroaching upon each other, but never 
interfered with by the remaining components; are porphyritically 
developed in a vesicular ground-mass, consisting mainly of 770” 
ee bea numerous small lath-shaped twinned Séspors. and a a 
byroxene, 
Z. 
io) Quartz Gabbro: Carrock FELL. Plagioclase i in phe - 
lates (some very clear, others kaolinised), with quarts filling up all - : = 
the interstices, a of a ae reddish-brown tint, phic = - a 
