406 brownrtdge: boulders ly coal measures at wortley. 
coal. The other three boulders (or pebbles) are quartzites and much 
smaller in size, varying from 11 in. by 9 in. to 3^ in. by 2| in., and 
were all found embedded in the black bed coal itself. Two of the 
specimens are more angular in general shape than the third, but in 
all of them the angles or edges are well rounded off, and the faces 
polished. 
Mr. T. G. Bonney, F.R.S., &c., to whom two sections of the 
quartzites have been submitted, kindly describes them as follows: — 
" The grains in the rock are remarkably well rounded, the 
" majority are quartz but there are some grains, also rounded for 
" the most part, which are brown in color, more or less opaque. I 
" I think it possible that these are decomposed felspar, stained by 
" infiltrated bituminous material. The quartz grains are cemented 
" by secondary quartz, sometimes, but not always, in optical 
" continuity with the adjacent grains. Cavities appear to be frequent 
" in most grains, but are generally of very small size ; sometimes a 
" tiny bubble may be noted, but I think that they are commonly 
'* empty, some grains contain a number of small almost colorless 
" belonites, rather like sillimanite, which are commonly seen in the 
" quartz of certain old granitoid rocks ; others contain a flake of 
" brown mica, a tiny crystal or two, probably an iron oxide or a 
"crystallite which may be zircon. I expect the quartz has been 
" derived from an old granitoid rock. The well rounded grains 
difference this specimen from those quartzites or grits which 1 have 
" hitherto seen from boulders in coal, but a specimen which I 
obtained from one of the old quartzites of the Lickey Hills also 
" contains many well rounded gi^ains, and so does a quartzite in the 
Charnwood series, of course I do not mean to suggest that we must 
" look in this direction for the parent rock." 
Of a second specimen Mr. Bonney remarks : — " This rock differs 
"but little from the last, the grains, as a rule, I think are not quite 
" so well rounded, and rather more are stained; those containing the 
"belonites are perhaps not quite so common. A small grain may be 
" brown tourmaline, and I think this mineral is also included in a 
" quartz grain. It is very probable that this boulder comes from the 
" same parent rock as the other one." 
