Feb., 1892. 
PERMIAN BRECCIA OF LEICESTERSHIRE. 
33 
mentioned, with a few grains of magnetite, and fragments of a 
grit. The last is composed of angulaf bits of quartz, felspar 
more or less decomposed, perhaps also decomposed volcanic 
glass, and grains of a greenish chloritic mineral and iron oxides, 
all cemented by a brownish-green paste. The green mineral is 
probably due to the decomposition of basaltic or andesitic 
detritus. Part of the specimen is simply a fine-grained grit, 
but I suspect that materials of volcanic origin varying from 
moderately basic to somewhat acid enter directly or indirectly 
rather largely into the composition of this rock. It does not 
occur at Charnwood, and the fragments in it do not remind 
me strongly of any rocks in that region. (34.) A grit with 
many well-rounded grains both of quartz and of more than 
one variety of a fairly acid igneous rock. (12.) A subangular 
fragment of hard dull-red quartzite, composed of ( a ) quartz 
grains, subangular to well-rounded ; these look rather dirty 
from the presence of minute cavities, some apparently empty, 
but many with fluid enclosing small bubbles, which do not 
exceed about one-sixth of the volume, and are commonly less. 
A few grains show a compound structure, and one, larger than 
the rest, seems to be a quartz schist ; (6) a few fragments of 
devitrified rhyolite (sometimes larger than the quartz, and 
rather angular), certain of which are not unlike the rhyolitic 
rocks of Charnwood. One, however, shows a distinct 
perlitic structure, which I have never seen in any Charnwood 
specimen. Three larger fragments of igneous rock are enclosed; 
one contains many variously-shaped patches of chlorite, and is 
considerably altered ; perhaps it is a rather basic, ashy rock ; 
another probably is a fine-grained ash of a more acid type, 
and a third—smaller—is an ashy argillite. Each grain of 
quartz has an external coating of haematite, and the interstices 
are filled with crystalline quartz (not in optical continuity with 
the grains), in which little tufted crystallites of haematite 
often occur. (11.) A piece of a subangular fragment 
of a light - coloured, speckled volcanic grit. Under 
the microscope it is seen to consist of some frag¬ 
ments of decomposed felspar, probably ortlioclase, two 
or three of quartz, and the remainder fragments of 
devitrified volcanic rock ; a few of these are darkened with 
opacite or ferrite. Of the rest, some contain felspar micro- 
liths, others appear to have been glassy dacites or rhyolites. 
Yiridite and ferrite have formed in the dusty matrix. The 
rock reminds me slightly of some of the volcanic series of 
the Wrekin. (39.) A well-rounded ovoid pebble of grit about 
3Jin. long. This was obtained from the Coton Park and 
Linton Colliery. It consists of quartz in angular, sub¬ 
angular, and even rounded grains, with angular and sub- 
