174 ME. H. H". ARlfOLD-BEMROSE 01^ A. QUARTZ-llOCK [May 1898^ 



a short course. In these veinlets the quartz-crystaJs often penetrate 

 one another or are arranged in clusters, the structure of which is 

 like that of the quartz-rock. The separate crj'stals have no 

 apparent connexion with the veins, hut are irregularly distrihuted 

 throughout the remainder of the slice. A little lower down the rock 

 contains no quartz in some places, and no residue when dissolved in- 

 acid. 



No. 749, below the limestone from which jSTo. 431 was taken. 

 In a hand-specimen, this appears to be either the junction of the 

 quartz-rock with limestone, or, what is more probable, a vein of 

 quartz-rock in the limestone. The greater part of the thin slice 

 consists of quartz-rock, which diifers from that of the ordinary type 

 by the presence of a few small patches of crystalline calcite between 

 the quartz-grains. There is a fairly sharp line of division between 

 this and the other portion of the slice. The latter contains much 

 more calcite and larger quartz-grains, which are often idiom orphic 

 crystals. It is traversed b}^ two small veins of quartz roughly 

 parallel to the junction-line. Some of the quartz contains calcite^ 

 There are traces of fluor present. 



{e) Field east of, and adjoiniDg Pounder Lane. 



In the field immediately east of Pounder Lane are several large 

 bosses of dark quartz-rock which often contains veins of fluor. At 

 the top of the field are two escarpments of oriinary limestone' 

 dipping 15° in an easterly direction. Lower in the series may be 

 seen ordinary limestone-beds on the same horizon as quartz-rock 

 and quartzose limestone with quartz-veins. Lower still, close to- 

 the lane, are several bosses of quartz-rock and limestone arranged 

 nearly parallel to the lane and on one horizon. Above the escarp- 

 ment are limestone-beds dipping in the same direction : these are 

 probably on the same horizon as the quartz-rock described above. 



The quartz-rock often contains holes as big as a man's fist.. 

 They are no doubt due to the weathering out of lumps of quartzose 

 limestone. Portions of the latter are often embedded in the quartz- 

 rock. In places the carbonate of lime has weathered out, leaving 

 loose quartz-crystals, which are easily washed away. The various 

 stages of this process may be seen. 



No. 547 is a quartz-rock, of the Top Lift type, containing fluor ill' 

 detached pieces and in plates which include quartz-crystals, re- 

 minding one of ophitic structure. The quartz-grains are generally 

 elongated, but do not possess crystalline outline. 



'No. 425, sp. gr. 2*65, a few inches from No. 547. Quartz-crystals 

 in calcite. The quartz generally possesses a crystalline outline, often 

 giving hexagonal cross-sections. Sometimes a hexagonal section at 

 right angles is seen embedded in, or on the edge of, a section parallel 

 to the axis, showing that the two penetrate each other at right 

 angles. In places the quartz-grains form an aggregate resembling 

 the quartz-rock. The crystals often contain calcite. The residue 

 consists entirely of quartz-crystals or clusters of the same. The- 



