ITALY. LETTER XXII. 299 



The marble of Carrara and Seravezza, and ge- 

 rally the cryftalline, fcaly, and coloured marbles, 

 fuch as thofe in the Sanefe and Genoefe, near Porto 

 Venere, &c. are found in large mafiy oblique 

 ftrata, fuperincumbent to each other, and, as far 

 as we know, entirely deilitute of petrifactions. 

 Every ftratum has its particular fifiures, which 

 commonly are filled with calcareous fpar, and 

 fometimes with quartz. At Seravezza the deeper 

 laying flate (Saffb morto) appears under the fuper- 

 incumbent marble. 



The marble of Porto Venere in the Genoefe is 

 yellow, mixed with black, and extremely beau- 

 tiful. 



Near Seftri, and in feveral other places, are dif- 

 ferent coloured marbles. 



At Lavagna they dig black table- flate, which 

 ferves at Genoa, and thereabouts., inftead of tiles. 

 It is employed likewife in the linings of oil- 

 cifterns; and is preferable to the common in- 

 cruftations of lead or plaifter, fince the acid in 

 the oil acts upon the iead, and even upon the 

 plaifter, if it be not entirely faturatpd with the vitri- 

 olic acid. This flate is, in Italy, called La- 

 vagna, on account of the place in which it is 

 found. 



Near Polzevera, in the Genoefe, is digging a 

 fort of rock, known under that name, confifting 



of 



