176 MR. H. H. ARNOLB-BEMROSE ON A QUARTZ-ROCK [May 1 898, 



No. 599 is a (^uartzite of the Top Lift type. A few small veins of 

 quartz run through the section. Some of the grains have a 

 crystalline outline, and contain rough zones or inclusions of calcite. 

 A similar rock was also found between Uppertown and Bonsall, and 

 near Brightgate. 



III. The NoRTHERisr Area. 



Specimens were examined from the following localities : — 



{g) Find ale. 

 (h) Bathamgate. 

 Ij) Brock Tor. 

 {k) Oxlow Rake. 

 {I) Doveholes. 



(g) Pindale. 



In about half-a-dozen fields which lie west of Pindale, and between 

 Dirtlow Rake and Bradwell Moor Farm (6-inch Map 10, S.W.), 

 the ground is fairly well covered with isolated blocks and masses of 

 quartz-rock. A few isolated blocks of similar rock are found 

 along the south side of Oxlow Bake, which is a continuation of 

 Dirtlow Bake. At the head of Pindale they often contain nodules 

 of chert. 



JSTo. 592, sp. gr. 2-52, quartz-rock, north side of Pindale, is a fine- 

 grained rock, consisting of quartz with a dark- coloured material 

 filling the spaces between the crystals. Under a 1-inch objective 

 the crystals are much elongated, and give lath-shaped sections like 

 felspars ; but they are not twinned, and always show straight 

 extinction. Their boundaries are not crystalline, but their edges 

 are often notched like the teeth of a cog-wheel, due to penetration 

 or interlocking of adjacent crystals. 



jSTo. 593, sp. gr. 2-50, is very similar to ISTo. 592, and the same 

 description will suifice. The block contains chert-nodules. A 

 nodule from another block contained part of a fossil shell. 



From the manner in which these blocks lie about on the grass, 

 it is impossible to make out their relation to the limestone-beds. 

 But on the opposite side of the valley of Pindale there is a boss of 

 rock which is on the same horizon as the limestone a few yards 

 away, and which in its occurrence and microscopical structure is 

 very similar to the Pounder Lane rock. 



This outcrop was carefully worked over, hammer in hand, all 

 ehips broken off being subjected to the lens. Five specimens were 

 selected, and thin slices were prepared from them. 



j^o. 586, sp. gr, 2-60, consists of quartz and fluor. The latter 

 mineral occurs in irregularly-shaped patches, enclosing small 

 prisms of quartz terminated by pyramids, and reminding one of 

 ophitic structure. It has an uneven violet colour, and contains 

 many cleavage-lines, which meet at angles varying from 63° to 78°. 

 The greater portion of the slice is composed of quartz, the crystals 

 of which interlock. 



