spencer: GNEISSOID granite in the HALIFAX HARD BED COAL. 97 
microscopic analysis, the most notable feature about it was its 
spherical and highly polished form. It was a hard white rock streaked 
with patches of darker hue, and of about the size of an orange ; it 
had evidently been subjected to a great deal of attrition. 
About the same time, my frieud, Mr. George Lister, had a fine 
quartzite boulder brought to him which was found in the Low Moor 
(near Bradford) Better Bed Coal. It was about the size of an ordi- 
nary football, and he informs me that the boulders in this locality 
were not very rare. 
Since that time boulders of quartzite and other rocks have been 
found in coal beds in various places in the Midland Coal-fields, and 
also in Lancashire and Derbyshire, some of which were described by 
Professor Bonney in his presidential address to the Geological Section 
of the British Association at Birmingham in 1886. In the spring of 
last year two or three quartzite boulders w^ere recorded by Mr. C. 
Brownridge, F.G.S., from the Black Bed Coal at Leeds. Two of these 
were subsequently sent to the writer to cut and mount sections for 
examination under the microscope, and a thin slice of each specimen 
was sent by Mr. Brownridge to Professor Bonney for examination, and 
have already been described." 
hi the spring of the present year, 1888, I was very fortunate in 
obtaining from Shibden Head Pit, near Halifax, a boulder of a most 
interesting character, which had recently been found in the Hard Bed 
Coal. The specimen is of a greyish colour, about four inches in 
length, by about two and a half square. The angles have been worn 
off, and the faces pohshed and striated transversely. The striae are 
most probably due to slickensiding in the coal rather than to glacia- 
tion. After preparing thin slices for examination under the micros- 
cope, it was evident that the specimen presented a different structure 
from either of those recorded from the Black Bed Coal at Leeds. Upon 
receipt of a section of this boulder, Professor Bonney replied as 
follows: — ''The boulder is one of unusual interest. It is not a 
quartzite but a granitoid gneiss or gneissoid granite, probably derived 
from some mass of pre-Cambrian age." "The specimen practically 
" consists of two minerals, quartz and felspar. The former occurs in 
*Proc. of the Yorkshire Geological and Polytechnic Society, vol. ix., p. 405. 
