230 



SCHORL ROCK. 



Upper 

 Gallery. 



Wall -cases 

 6 and 7. 



(Map No 



laceous. It is remarkable, also, that the granitic veins and 

 dykes (elvan courses) of the neighbouring country, and 

 which may readily be supposed to be connected, at various 

 depths, with the main mass of granite, are frequently 

 schorlaceous. 



This schorlaceous granite generally appears to prevail 

 when a peculiar kind of argillaceous slate is brought into 

 contact with the granitic mass, such slates when near the 

 latter having also a schorlaceous character. There would 

 seem to have been a reciprocal and chemical action alon°- 

 the line of junction, when the whole was in a heated 

 state. 



Roche Rock forms a conspicuous object in the country, 

 rising abruptly from an undulating surface of elevated land, 

 constituting a portion of a mass of schorl-rock, which has 

 an east and west direction. 



Although this portion of the schorl-rock rises abruptly 

 above the surface of the adjoining land it is by no means so 

 hard a substance as might at first sight be supposed ; hence 

 when employed as a building stone, however ornamental its 

 appearance, it would not, probably, be attended with the 

 success that might be otherwise anticipated. Map 30. 



62. — Schorl-rock, composed of schorl and quartz in 

 nearly equal proportions. Map 33 — Laity, near Lelant, 

 Cornwall. 



63,— Schorl-rock, composed of small grains of schorl 

 and quartz, with occasional included fragments of the latter. 



Map 



ovely Beacon (No. 43) passes into this 

 •North end of Belovely Beacon, Corn- 



Schorl, shewing a tendency to form prismatic crys- 



rock. 

 wall. 

 64. 



tals in places. From a mass in Schorl Rock, 

 Botallack Mine 



65— Schorl, illustrative of the numerous schorlaceous 

 veins which are found in the district ; these (sometimes 



several inches in thickness) are composed of little else than 



Map 





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