170 T, G. BONNEY AND F, T. 8, HOUGHTON ON MICA-TRAPS 
Waterline eer eae 2°87 
CO yess ee. pein: 4°84 
SiOLemuiesuwed ae ee 46°17 
AlcOs this aera ae 16°95 
Fe Onhne sock edge 5:46 
BeO) 32) wie penis eee 0°83 
Min! 2 ho eu etre cutee 0-10 
CaQnr ee ree a 10-23 
IMO ae eSNG: Oak eckstes FAS 
KOE Ec ease a 3°96 
Niet Ojeda le: oe 9-49 
100-96 
Although the present condition of the rock makes it difficult to 
speak with certainty, we may venture, notwithstanding the amount of 
potash, to call it a diorite rather than a syenite. At any rate the 
amount of mica is not sufficient to warrant our retaining it among the 
mica-traps. 
This dyke is intrusive in Bannisdale Slates. It is more than 
20 feet wide, can be traced along the course of a stream for several 
hundred yards, and probably extends much further. It includes a 
large fragment of the Bannisdale beds, but neither this nor the ad- 
jacent rock are much altered. 
(4) Dyke, Stile-end Farm, between Kentmere and Long Sleddale*. 
Characters.—Macroscopic. The rock appears very finely crystal- 
line, the component minerals being much too small for recognition, 
and is of a dark-grey colour. 
Microscopic. The rock is a crystalline mixture of plagioclase 
(labradorite), hornblende, and iron peroxide (probably hematite). 
The first occurs in long, narrow, twinned crystals, like those common 
in dolerite. The second, partly in small well-defined prisms, of a 
clear olive-brown colour, rather free from ferruginous microliths 
(this variety is strongly dichroic); partly as a more filmy, fibrous, 
less well-defined, pale green variety, which barely shows dichroism, 
is associated with ferrugiuous microliths, occurring both together 
with and apart from the other, and having much more the aspect of 
a secondary product. It is possible that there may be also some 
little biotite. The iron-peroxide occurs both as grains of a more or 
less definite crystalline outline, and as isolated or aggregated minute 
rods or clubs (such as are figured by Borickyt). SBelonites are 
numerous, almost certainly of secondary origin. They pierce through 
both the felspar and hornblende, and are commonly from -0001 to 
-0003 inch in diameter. One or two of the largest seem to be of a 
very pale green colour, and resemble actinolite. If not this mineral, 
they must be zeolite. Apatite seems very scarce. Besides the above 
there are some larger crystals. Of these one set are much decom- 
* About 5 miles to N. of Staveley, and so out of the line. 
t Bohm. Basalt. pl. i. 
o_o 
