Mr. Weaver on the Geological Relations of the South of Ireland. 13 



jn which are disseminated crystals of yellowish white felspar, and also crystals and globular 

 portions of brownish grey vitreous quartz, and a few scales of mica. 5. A base of quartz, coloured 

 by clay-slate, and partially also by hornblende or chlorite ; a compact greenish grey, or greyish 

 green rock, containing incidentally particles of hornblende and crystals of glassy felspar, and some- 

 times grains of vitreous quartz. Without attention it may be confounded with greenstone. 



Hornstone.- — 1. In its simple forms, splintery or conchoidal. 2. Containing crystals of glassy 

 felspar, or flesh-coloured crystals of felspar, or both conjointly, forming a handsome porphyry. 

 The base is often of a yellowish, and sometimes of a hair-brown colour, and in the base a portion 

 of steatite is sometimes diffused, and the rock then becomes unctuous to the touch. 3. Hornstone 

 forming the base of the compound described under the head of Quartz-rock No. 4. 



Quartz Conglomerate and Hornstone Conglomerate,coarse- and fine-grained. — A base of quartz or 

 hornstone (or partially of compact felspar), much incorporated with steatite, and thus acquiring a 

 saponaceous feel, and containing crystals both of dull and glassy felspar ; as does also the green 

 steatite when appearing in a distinct form, which is frequently the case. This base envelopes nu- 

 merous fragments of quartz, hornstone, and hornstone porphyry, those of the two latter varying 

 sometimes from the smallest size to that of blocks of one and two feet in diameter. 



Red Conglomerate, Red Sandstone, and Red Sandy Slate. — These all contain numerous scales of 

 silvery mica. The conglomerate and sandstone are compounded principally of rounded and angular 

 fragments of quartz and red slate, connected by a basis of similar composition but smaller grain, or 

 by a simple base of quartz or reddish slate. In the mixture some grains of decayed felspar may 

 also be incidentally observed. The compound is sometimes greyish as well as reddish coloured. The 

 ingredients in the conglomerate rarely exceed the size of cherries, but sometimes extend to that 

 of turkey's eggs, and even a man's head, in magnitude. When the slaty basis predominates, a sandy 

 slate is formed '. These beds are sometimes associated with irregular masses and beds of quartz, 

 from an inch to one, two, and three feet wide, which bear a great quantity of beautiful, deep green 

 chlorite. 



Greenstone and Compact Felspar. — 1. Compact greenstone, a base of compact felspar, coloured 

 greenish grey by hornblende, and containing particles or crystals of hornblende, and sometimes also 

 crystals of felspar, thus appearing as a porphyry. The felspar base acquires a white aspect by 

 weathering. 2. Sub-crystalline greenstone, a confused intermixture of greenish grey glassy felspar 

 with hornblende, being also spotted with blackish green hornblende. 3. Compact reddish brown 

 or purplish felspar, partially intermingled with chlorite, or green steatite, and containing also 

 minute crystals of glassy felspar, -i. Greenstone conglomerate, a base of greenstone, enveloping 

 portions of greenstone, mostly of an angular form. 



The sub-crystalline greenstone seldom occurs in a distinct form on this coast. The compact 

 greenstone, which more generally prevails, exhibits a difference of character according to the state 

 in which the hornblende enters into the composition, the greater or less prevalence of siliceous 

 matter, and the intimate blending of chlorite. If the hornblende be unaltered, the rock is rugged 

 and stony ; if partially decomposed it is saponaceous. It is probably to this unequally aflected 

 state of the hornblende that the unequal state of aggregation in the greenstone is partly due ; and 

 that one portion consisting of comparatively loose materials is found serving as a base to numerous 

 harder portions which are embodied in it ; a difference ascribable to disturbance during the process 



' These rocks, like analogous productions in Kerry, &c., are not to be distinguished by mere 

 mineralogical character from varieties which occur in the old red sandstone of the carboniferous 



