

xxiv 







Hardness. 



Werner's 

 account. 



Slaty 

 Schistosa 



Scaly 

 Squamosa 



Sparry 

 Spathosa 



INTRODUCTION. 



Composed of thin layers or beds, as slates. 

 As the preceding was more peculiar to the 

 crystallised, so is this to the rupestrious fos- 

 sils. As this is rather a character of struc- 

 ture than texture, probably it might be 

 omitted here. 



f Composed of a congeries of small scales. Pe- 

 1 culiar to the plumbago, according to Estner. 

 Composed of a congeries of irregular crystal- 

 line parts, like coarse salt, as the coarser 

 kinds of scaly or saline limestone, as that of 

 Sala in Sweden, some hornblende-schistus. 

 This belongs to the granulated of the Wer- 

 nerian school. 



" In judging of the texture, attention must be paid, when 

 it is not of the compact kind, but of the fibrous or lamellar, 

 that it is inspected in a proper direction, which is that of its 

 parts j otherwise, when in the opposite direction, the fibrous 

 may appear granulated, and the lamellar radiated." 



Dr. Townson says that the structure is a particular dispo- 

 sition of the texture, as Hornblende-slate may have a sparry 

 texture and schistose structure; some iron ores, an earthy 

 texture and columnar structure. Of the Structure he only 

 indicates four kinds : 



Slaty, Testaceous, Concentric, Columnar. 

 The first is too general, the three others too rare, to be of 

 real utility in a general system ; and this confined use of the 

 word Structure would interfere with its general use in other 

 senses equally appropriate. 



The HARDNESS, another grand characteristic, may be best 

 illustrated in Werner's own words, which will at the same 

 time serve to convey some practical admonitions to the 

 student. 



" After the particular generical characters discovered by 

 the sight, in solid fossils, follow those which may be observed 

 by the feel, the first of which is hardness, forming the tenth 

 in the general system. 









