TAB. LXXXVIII. 



S I L E X Quartzum. 



Flint Pebbles, $c. 



Class 2. Earths. Order 1. Homogeneous. 

 Gen. 4. Silex. Spec. 1. Quartz. 

 Div. 3. Amorphous. 



Syn. Flint. Kirw. v. i. SOI. 

 Feuer Stein. Emmerl. v. 1. 143. 

 Quartz agathe pyromaque. Uaily, v. 2. 427. 



Jtlint pebbles, so universally known in the vicinity of 

 London, are not so well known every where, even in Great 

 Britain, since one may travel many miles in some counties 

 without finding any. 



The forms and colours of common flints are extremely va- 

 rious, and they give strong indications of being formed by in- 

 filtration and aggregation among the softer argillaceous rocks : 



CO D O O ' 



as the agates, &c. seem to be among the harder rocks of a si- 

 milar natrue; see p. 1 70: the siliceous infiltration being more 

 or less coloured by oxide of iron, gravitates, or aggregates, 

 into various forms. 



The upper pebble at the right hand is white at one end, 

 • gradually becoming grayer towards the other end, with a 



