202 EELIQUI^: AQUITAJSTICJE. 



XVIII. 



FLINT ITS NATUEE, CHAEACTER, AND ADAPTABILITY FOE IMPLEMENTS. 

 By Professor T. EUPERT JONES, F.E.S., F.G.S. 



[These notes on Flint were written at the late Mr. Henry Christy's request in 1864 or 1865, and set up in 



type by his desire soon after.] 



FLINT, the well-known hard stone out of which so many old Implements have 

 been fashioned, is more or less abundant in nearly all Chalk districts. It is, 

 indeed, found in one condition or another (flint, hornstone, chert, chalcedony, &c.) 

 in most limestones, whether soft and earthy (like Chalk), solid (like the Portland 

 stone), or hard and crystalline (like the Mountain-limestone of Derbyshire and 

 other calcareous rocks of even older formations). 



Flint occurs both as extensive sheets and as lumps or nodules, generally in 

 regular beds, and sometimes as veins crossing the bedding. It is fine-grained or 

 homogeneous consisting of silica, such as is also seen in the form of rock-crystal 

 (quartz), but not so pure, containing some iron, clay, lime, or other impurities, 

 besides having rather more water in its composition. 



It is often found as gravel and shingle ; and in that state it is the flinty ruins 

 of Chalk or other limestones that have been broken down and worn away by frost, 

 torrents, and sea- waves. 



In the Chalk, flint usually presents itself in irregular lumps, blackish within 

 and white without, breaking up (by frost or under blows) with a clean fracture 

 and sharp translucent edges. It sometimes shows evidence of the presence of a 

 Sponge, or some sponge-like organism, inside it ; and other fossil bodies are often 

 seen in it. This silica, indeed, was once in solution in the water, and, either sepa- 

 rating from the calcareous mud that subsequently became Chalk or permeating 

 it, has been accumulated in and about the Sponges, not only changing them, but 

 some of the surrounding Chalk, into its own substance ; for frequently a layer of 

 greater or less extent of the calcareous material, before or after its hardening, has 

 been converted atom for atom into flint, excepting the shells of Mollusks of the 

 Oyster group, and the tests and ossicles of different kinds of Echinoderms (Sea- 

 urchin, Starfish, and Stone Lily). In the Portland stone, the oolitic structure is 

 preserved in the transmuted flint bands ; so also the organic structure of small 

 fossils in some of the flint of the Polyzoan limestone of Central France ; whilst in 



