130 Br. Berger ow the physical Structure 



fracture often concholdal, breaking Into large broad flakes with 

 sharp edges ; it is also frequently striped with red, which appears- 

 to be owing to the oxide of iron it contains ; small threads of tender 

 yellow steatite are seen running through it, and it is often traversed 

 by veins of whitish asbestos. The course of these veins is very 

 straight, and by their intersections they form nearly regular rectan- 

 gular pieces, thus disposing the rock to break in those direc- 

 tions.* Sometimes this serpentine passes into a hard steatite, dis- 

 posed in curved laminse, and having at the same time a fibrous 

 fracture. 



The mica slate of the most southern part of the Lizard has a 

 very brilliant lustre, is ofa fawn colour, includes veins of quartz, and 

 is evidently stratified. I was not able to discover any garnets in its 

 composition. 



By soap-rock is meant a kind of steatite, so tender that it may be 

 cut as easily as new cheese. It is imbedded in the serpentine. Its 

 colour is a pearly white or grey with red and blue veins, and when 

 pure it has a sort of semi-transparence. On coming out of the 

 quarry, it may be kneaded like a lump of dough, but after having 

 been exposed to the air for some time, it becomes friable, owing, no 

 doubt, to the evaporation of the great quantity of water it contains ; 

 it possesses the soapy feel in the highest degree, and pieces of hard 

 stone are included in it, in pretty large quantity. It is used in the 

 manufacture of porcelain for the same purpose as the kaolin, and on 



* On the summit of the mountain de la Garde near Genoa, Saussure observed a gra- 

 nular serpentine, which divided naturally into polyhedral fragments, most frequently 

 ofa rhomboidal form. Voyages dans Ics AJpes, § 1342. 



On the road from Nice to Frejus, the same geologist found another kind of serpen- 

 tine, which divided into irregular polyhedral masses. Ibidem. § 1434. 



