62 Prof. T. G. Bonney and Miss Catherine Raisin— 
penninite of Lévy), epidote, a carbonate (sometimes replacing 
felspar), azeolite, iron oxides, kaolin, and possibly augite granules. 
The brecciated ‘spilite’ from the northern side of the quarry 
contains angular or sub-rounded fragments with a slightly blackened 
or iron- stained edge. In these fragments the fresh-looking microliths 
of oligoclase indicate a flow structure. The intervening agoregate 
exhibits extremely minute crystalline specks, but, ome to the 
disseminated ferrite, it is difficult to decide whether this can be 
resolved completely into individualized minerals, or may possibly 
include some remains of original glass. Some of the porphyritic 
felspars are plagioclase; others (clearer crystals) resemble the tabu- 
lar Carlsbad twins of sanidine; these sometimes form a diverging 
group. Rather irregular, often elongated patches of chlorite have 
apparently filled original vesicles microscopic in size. The matrix 
in which the fragments are imbedded consists of broken felspar, 
possibly of some quartz, and of dusty materials, probably containing 
minute granules of epidote or perhaps augite. This matrix, which 
is not very different from the ground-mass in the fragments, is 
somewhat banded. It is thus evident that the rock is a volcanic 
agglomerate. 
The solid purple ‘‘spilite,” from the northern end of the western 
face in the quarry, consists mainly of crowded felspar microliths and 
of interstitial material, which is either a clear viridite or a decomposed 
and cleaved mineral, and probably represents the pyroxene of a micro- 
ophitic ground-mass. Much opacite and small flakes of haematite 
are associated. One porphyritic crystal seems very probably to have 
been an augite (now largely replaced), and other more irregular 
patches of secondary minerals may have had a like origin. The 
porphyritic felspars are much decomposed. Some, however, exhibit 
twinning on the Carlsbad type, with which in certain cases 
oscillatory twinning is combined. This also occurs by itself. The 
usual long lath-like microliths are less frequent in the matrix of 
this than of other varieties, the crystallites sometimes having a 
rather stumpy or more irregular step-like outline. 
In the amygdaloidal “ spilite ” from the southern face of the quarry 
the ground-mass was probably originally micro-crystalline; the small 
lath- “shaped felspars are well-preserved, but the augite is replaced 
by granular aggregates, which sometimes occupy long prismatic 
spaces. Hpidote is abundant in some parts, especially ‘around the 
amygdules. The porphyritic felspars are large and fairly clear, but 
they include scattered kaolin and epidote which in some eases may 
result from the alteration of included magma. One crystal exhibits 
two arms which might belong to a Baveno grouping of a plagioclase 
series. ‘The green pseudomorphs of porphyritic crystals which were 
probably augitic are fairly abundant. The numerous and large 
amygdules contain viridite, epidote (often intercrystallized with a 
small amount of a water-clear mineral, evidently later than the 
epidote and resembling quartz), calcite, or an allied carbonate. 
Sometimes these secondary minerals form successive zones within 
a vesicle; and they also occur in the ground-mass, in veins, and 
within porphyritic crystals. 
