348 W. C. Simmons — Granite of Foxdale, Ide of Man. 



druses, called ' lochs ' by the quarry men, are said by them often to 

 contain water. Now the veins are much jointed and cracked, and 

 after breaking open many blocks with druses we succeeded in 

 finding one or two containing water, but which evidently had filtered 

 in along the cracks, as attested by the iron-stained path taken by it. 

 All the quartz veins in the Foxdale Silica Quarry are of one type. 

 They consist of almost pure quartz crystallized on a large scale, some- 

 times with flakes of mica. These are the quartz veins proper. At 

 Eairy Quarry we get also fine-grained quartz-mosaics, forming the 

 vein instead of the large crystals seen at Foxdale Quarry. 



The Eairy Quarry (see Map, Plate XVI, and Section, Fig. 3, p. 349). 



It is here that a junction of the slate with the granites may be 

 seen, and here are thick pegmatite and quartz veins, with microgranite 

 and granite giving an interesting section. The Figure (Fig. 3) explains 

 itself. There is here much glacial drift covering the rocks, giving 

 in one case quite a peculiar fold to the fragments. 



The junction of the slates with the granite is quite a normal one, 

 and the former are altered to mica schists and phyllites close to the 

 granite. If the Eairy granite mass has been thrust off from the larger 

 Foxdale mass, then the junction and slates too must have been 

 subjected to the thrust. This does not seem probable, but evidence 

 is wanted to prove that the slates are continuous with the main mass 

 of the country rock. It should be noted that in few places are the 

 slates so altered as between the two outcrops of granite. In the 

 quarry section, next to the junction, a thick mass of jointed pegmatite 

 cuts across the granite and slates (Fig. 3, P, P). It consists of quartz 

 with large spangles of mica. The joint planes run at a steep angle to 

 each other, and between the planes in two or three places a deposit of 

 brown powdery limonite occurs, in one case as much as a foot thick, 

 but shading off rapidly upwards. This is bounded further in the 

 quarry by several faults with quartz and microgranite between them. 

 These faults are also full of limonite. The mass of microgranite next 

 shown is a fine granite very similar to the normal microgranite dykes 

 associated with the granite. It is in parts stained by infiltered 

 limonite and haematite along the joints which make dendritic 

 markings, comparable with those found on Windy Common to the 

 south, mentioned later. 



A thick vein of quartz follows with a dip of about 75° to the east. 

 This sends an offshoot into the microgranite. Lastly, there is another 

 quartz vein separated from the former on both sides of the quarry by 

 a wall of granite, but they run together through the granite in the 

 centre. These last two veins of quartz contain little mica, but are 

 much stained by infiltered iron-bearing water to yellow, brown, 

 and red. 



Mr. Harker describes the Foxdale granite thus: "It consists of 

 quartz, microcline, an acid plagioclase, muscovite, subordinate biotite, 

 and little crystals of garnet and zircon. In the marginal part of the 

 intrusion are developed bands and masses of pegmatite, thick veins 

 and bands of greisen, and finally quartz veins containing only local 

 aggregations of white mica or bordered by a narrow seam rich in that 



