81 



unfortunately inaccessible to man, two caverns 

 open in the form of crevices. We were assur- 

 ed, that they are inhabited by the same noc- 

 turnal birds, that we should soon become ac- 

 quainted with in the Cueva del Guacharo of 

 Caripe. Near these caverns we saw strata of 

 schistose marl, and found with great astonish- 

 ment rock-crystals, enchased in beds of alpine 

 limestone. They were hexaedral prisms, ter- 

 minated with pyramids, fourteen lines long, and 

 eight thick. The crystals, perfectly transparent, 

 were solitary, and often three or four toises 

 distant from each other. They were enclosed 

 in the calcareous mass, as the quartz chrystals 

 of Burgtonna*, and the boracite of Lunebourg* 

 are contained in gypsum. There was no crevice 

 near, or any vestige of calcareous spar 



We reposed ourselves at the foot of the ca- 

 vern, whence those flames were seen to issue, 

 which of late years are become more frequent. 

 Our guides and the farmer, an intelligent man, 



* In the duchy of Gotha. 



t This phenomenon reminds us of another equally rare, 

 the quartz crystals that Mr Freiesleben (Kupferschiefer, t. 

 ii, p. 89) found in Saxony, near Burgcerner, in the county of 

 Mansfeld, in the middle of a rock of porous limestone (rauch- 

 wakke), lying immediately on the alpine limestone. The rock 

 crystals, which are pretty common in the primitive limestone 

 of Carrara, line the insides of cavities in the rocks, without 

 being enveloped by the rock itself. 

 VOL. III. G 



