Feb., 1892. 
PERMIAN BRECCIA OF LEICESTERSHIRE. 
27 
sequent pressure. (67.) The next is from a subangular 
fragment of a compact purplish, somewhat slaty-looking rock, 
in which felspar crystals are so irregularly scattered as to 
suggest a fragmental origin, but under the microscope, the 
rock closely resembles some of the compact purple rhyolites 
which occur as fragments in the agglomerates of Charnwood, 
and to these, on the whole, I am disposed to refer it. (47.) 
The next is an angular fragment with rounded edges, the 
matrix of which corresponds very well with that of the 
compact purple rhyolitic rocks of the Charnwood breccia, 
but it has two or three irregular vesicles filled with a pinite- 
like mineral,* a structure which, so far as I know, they do 
not exhibit. (26.) A brecciated rock infiltrated with quartz. 
It is difficult to speak with certainty, but, on the whole, I 
incline to the view that the rock is a rhyolite, which has 
been rather decomposed, brecciated, and permeated by silica. 
The cracks are filled with regular grains of crystalline 
quartz, and contain some irregular patches of a dull green, 
cliloritic mineral. These veins also present a rather brecciated 
aspect, as if the rock had been again disturbed after infiltration. 
(9.) An angular fragment of quartz-porphyrite of a warm, 
light red colour, somewhat speckled. Under the microscope, 
the ground mass, which is much stained with ferrite, appears 
to be wholly crypto-crystalline. In it are scattered a fair 
number of (a) crystals of rather decomposed felspar, many 
(perhaps all) of which are plagioclase ; (6) numerous granules 
of quartz, occasionally showing some of the crystal angles, 
usually clear, but sometimes with enclosures of the ground 
mass ; (c) an altered ferro-magnesian mica, now of a dull 
greenish colour, with the iron oxide partly separated; (d) a 
few larger grains of iron oxide; (e) some small crystals of 
apatite. (29.) A fragment which appears to be a fine-grained 
felstone, with small crystals of felspar and hornblende and 
grains of quartz scattered about in a rather compact matrix. 
The rock does not, as far as I know, exist at Charnwood, but 
might possibly be related to the “ syenites ” of that region. 
(19.) A decomposed and devitrified igneous rock, with some 
crystals of felspar, past further recognition, and (?) altered 
biotite ; also, some altered iron oxide and perhaps a little 
quartz. The rock probably has been once a sanidine-trachyte 
or an andesite. It does not remind me strongly of any Charn¬ 
wood specimens, being more micaceous than is usual in the 
uncrushed rocks of that district. (81.; A rather speckled, 
greenish-grey rock, becoming paler in weathering ; it appears 
*Cf. “ Quart. Journ. Geol. Soc.Vol. XLII. (1886), p. 187, G. A. J. 
Cole, “On the Alteration of Coarsely Spherulitio Rocks.” 
