128 DOMAIN IX. ANOMALOUS. 



ciilar large granular masses, so that the topaz 

 rock appears large granular in the great : a kind 

 of structure which is termed slaty granular. The 

 drusy cavities, that sometimes occur between 

 these concretions, frequently contain regular 

 crystallised topaz and quartz; sometimes also 

 schorl and lithomarge, of the same colour as the 

 topaz. 



" 2. Its stratification is uncommonly distinct. 



" 3. Its geognostic position has not been hi- 

 therto satisfactorily ascertained. It appears to 

 lie on gneiss, and under clay slate. 



" 4. It is a very rare rock, having been hi- 

 therto found only in one place in Germany, near 

 the town of Auerbach, in the Saxon part of 

 Voigtland, where it forms a mountain mass of 

 considerable extent, and is there known by the 

 name of Schneckenstein. A rock, composed of 

 topaz, beryl, quartz, and lithomarge, occurs in 

 the mountain of Odontschelon, and in the neigh- 

 bourhood of Mursinsk, in Siberia, which resem- 

 bles topaz rock, and is suspected to be the same 

 with that of Auerbach. The schorl-rock of 

 Cornwall is probably very intimately connected 

 with topaz rock."* 



It is truly surprising, that what are called the 

 geognostic relations of so remarkable a rock 



* Jameson's M in. iii. 141. 



