of Boston and its Vicinity 



179 



y- 



Chymical Characters, 



Before the blowpipe it fuses into a greenish or blackish grey 



enamel. 



Geological Situation and Localities, 



It occurs in beds in Argillite, into which it passes, at Charles- 

 town, Maiden, Quincy, and in rolled masses at Cambridge, 

 Brookline, Dorchester, &c. 



Use* 



Some of the finer varieties may be employed for giving an 

 edge to cutting instruments* 



SPECIES XIK.^CLAY, 



Variety 1. — ^Potter's Clay. 



Potter's Clay, Cleavelandf p. 371. Earthy Claj, Jikin, p. 235. Earthy 

 Potter's Clay, Jameson, vol. i. p. 504. 



External Characters, 



Its colours are yellow and green. Of yellow, it occurs light 

 honey yellow, between honey and straw yellow; and of green, 

 it occurs pale asparagus green and greenish grey. The colours 

 are liable to variation from admixture of various foreign sub- 



stances. 

 It is dull. 



It is opaque. 



It is ami)rphous. 



When moisicued, it exhales a strong argillaceous odour. 



