256 THEORY of the EARTH. 



or continued in lines running nearly parallel. Thefe columnar 

 bodies of quartz are beautifully impreffed with a figure on the 

 fides, where they are in contact with the fpar. This figure is 

 that of furrows or channels, which are perfectly parallel, and 

 run acrofs the longitudinal direction of the quartz. This is 

 reprefented in fig. 4. This ftriated figure is only feen when, 

 by fracture, the quartz is feparated from the contiguous fpar. 



BUT what I would here more particularly reprefent is, the 

 tranfverfe fection of thofe longitudinal filiceous bodies. Thefe 

 are feen in fig. i. 2. and 3. They have not only feparately the 

 forms of certain typographic characters, but collectively give 

 the regular lineal appearance of types fet in writing. 



IT is evident from the infpection of this foffil, that the fpar- 

 ry and filiceous fubftances had been mixed together in a fluid 

 ftate ; and that the cryftallization of the fparry fubftance, 

 which is rhombic, had determined the regular ftructure of the 

 quartz, at leaft in fome directions. 



THUS, the filiceous fubftance is to be confidered as included 

 in the fpar, and as figured according to the laws of cryftalliza- 

 tion proper to the fparry ground ; but the fpar is alfo to be 

 found included in the quartz. It is not, indeed, always per- 

 fectly included or inclofed on all fides j but this is fometimes 

 the cafe, or it appears fo in the fection. Fig. 5. 6. 7. 8. 9. and 

 i o. are thofe cafes magnified, and reprefent the different figured 

 quartz inclofing the feld-fpar. In one of them, the feld-fpar, 

 which is contained within the quartz, contains alfo a fmall tri- 

 angle of quartz, which it inclofes. Now, it is not poffible to 

 conceive any other way in which thofe two fubftances, quartz 

 and feld-fpar, could be thus concreted, except by congelation 

 from a fluid ftate, in which they had been mixed. 



THERE is one thing more to be obferved with regard to this 

 curious fpecies of granite. It is the different order or arrange- 

 ment of the cryftallization or internal ftructure of the feld-fpar 

 ground, in two contiguous parts of the fame mafs. This is to 



be 



