'^ DOMAIN V. CALCAREOUS. 



cient, with brown veins, has been found in smalt 

 pieces at Mont Martre, near Paris; but those of 

 Spain are in rocky masses, and of great beauty. 

 It is said that the territory of Volterra, in Tus- 

 cany, affords no less than twenty remarkable 

 varieties*. 



r Voiterra. Those most esteemed are the agate-alabas- 

 ters, to which this name is given, on account of 

 their fineness; and the onyx-alabasters, which 

 present clear and distinct layers, of different co- 

 lours, all of them undulated and festooned, with 

 saliant and re-entering angles, like the zones 

 of fortification-agates, and of which the whole 

 forms a figure nearly circular. The formation 

 of these zones is owing to a play of crystal- 

 lisation, like that of agates ; and in like manner 

 they are always found exactly parallel among 

 themselves, whatever may be the irregularity 

 of their course. A perpetual circulation takes 

 place in the interior of the alabaster, while it is 

 still in its native site, which arranges the various 

 particles of which it is composed, according to 

 laws determined by their mutual affinities. 



" The onyx-alabaster is sometimes formed in 

 sheets on a horizontal plane; and then these 



* Patrin, iii. 110. In the catalogue of Davila, ii. 98, it ii 

 observed that the ancient alabasters were probably from Spain, a 

 the same sorts abound there. 



