MODE XIV. SILICEOUS GLUTENITE. 233 



other tracts of Saxony, no petrifactions or conchy- 

 laceous impressions are found in it, though in that 

 of Perna, adjoining, they are found. Charp. 24 

 and 26 : it sometimes reposes on horn-slate. 

 Charp. 24. 



" The mountain Steinthal, in the Vosges, of red 

 sand-stone, is considered, by Baron Diedrech, as 

 primeval. 2 Diedr. Gitts des Minerals, 209, 210. 

 The sand-stone mentioned in 6 Sauss. 81, which 

 alternates with primitive lime-stone, must also be 

 primitive."^ 



Brongniart, in his Mineralogy, has adopted 

 rather a singular distribution of the gres, that is, 

 grit or sand-stone, and arranges it immediately 

 after quartz. He informs us, in a note, that he 

 only here describes the pure and homogeneous 

 sand-stone, composed solely of quartz ; the other 

 stones, commonly called sand-stones, being placed 

 among the rocks, where they will be described 

 under the name of psammites. The stone which 

 he defines is composed of very small grains of 

 quartz, " agglutinated by an invisible cement." 

 It has therefore the hardness and infusibility of 

 quartz in its grains; but its texture changes the 

 aspect of its fracture, This fracture, always gra- 

 nular, sometimes scaly and even shining, without 



* Geol. Ess. 208. 



