C X35 ] 



ing 'fire with fteel, and by triture yielding a very 

 rough powder. 



Order V. Aggregate. Originating from a 

 mixture of the foregoing, the interftices ufually 

 filled up with quartz, fpar, or glimmer. 



Genera of Stones. 



I, H U M O S ^. Slaty Stones] 



%. ScHiSTUs, Slate. Bafe ; vegetable mould : 



breaking into. 

 Fragments j fiflile, horizon- 

 tal, plane, opakc, yield- 

 ing to the knife, and 

 combuftible. 



II. C A L C A R E iE. Calcareous Stones. 



2, MARMORi Marble. Bafe ; animal earth. 



Fragments indeterminate, 

 irregular, yielding to 

 the knife. 



Effervefcing with acids, 

 though not completely 

 foluble therein ; but 

 eafily falling into lime. 



3, Gypsum* Plaifter. 5^y^; calcareous earth, fa- 



turated with acid. 



Fragments indeterminate, 

 irregular, yielding to 

 the knife, component 

 particles impalpable. 



K 4 Fixed \ 



