MODE XVI. SIDEROUS OLUTENITE. 139 



in or under it. This singular rock has been termed 

 semiprototite by Mr. Kirwan, implying that it is 

 half primitive ; and he informs us that it is com- 

 monly found under coal, is micaceous, and con- 

 tains lumps of porphyry or granite. The grains 

 are generally quartz or keralite, the cement being 

 an irony clay, which imparts the colour. 



But as the passage affords some curious Ger- 

 man learning on the subject, from books little 

 known in this country, it shall be presented entire. 



" Semiprotolites (Rot he todt liegendesj. 



" These stones I call by this name, as being 

 partly of primeval, and partly of subsequent, ori- 

 gin : they consist of pebbles, or of fragments, or 

 of sand of primeval origin, compacted and ce- 

 mented by an argillaceous, or calcareous, or sili- 

 ceous cement, of posterior origin; hence they 

 generally form the lowest stratum that separates 

 primeval rocks and secondary strata. From their 

 composition, they come under the denomination 

 either of farcilites, brecias, or sand-stones. Iii 

 some places this sand has been accumulated into 

 vast heaps, so as to form mountains 6 or 700 feet 

 high, and then compacted by an adventitious ce- 

 ment. Of this sort are the mountains of Hertz- 

 berg and Kaulberg, near Ilefeld, in which the 

 sand is cemented by a ferruginous cement, and 



