t 6^ ) 



white. In the fractures we perceive that 

 they confift of a number of opake groups 

 of fibres, ftriated, filky, and (hining, which 

 diverge from the centre to the circumference 

 of the globules, and thus form fo many in- 

 verted cones. Thefe globules, fome of 

 which are more than four lines in diameter, 

 Jjerfedly fill the cavities of an argillaceous, 

 light, extremely friable lava of a deep grey 

 colour. Every cavity, however, does not 

 contain a zeolite of this conformation : in 

 fome we ftnd zeolitic ftones with feveral 

 facets, but fo confufed that the precife con- 

 figuration of the cryftals cannot be diftin* 

 guiftied. On attentive examination, they 

 evidently appear to be formed of th« fame 

 zeolitic fubftance, which, when it occupied 

 the whole fpace of the cavity, took the con- 

 formation of thofe fibrous groups that have 

 externally a globofe figure ; but when a part 

 of this fpace remained empty, it cryftallized 

 more or iefs. Thefe zeolitic ftones always 

 have" in the middle a fmall empty fpace, 

 where they are cryftallized, forming a num- 

 ber of very minute geodes. 



The 



I 



