224 TRAVELS THROUGH 



two large fine columns in the church delle tre fon- 

 tane alia Poria di S. Paolo. 



b. Serpentine nero antico, black, with large white 

 parallelepiped fpots, fimilar to thofe in the Serpen- 

 iino vercT antico , which, the colour excepted, is 

 entirely refemblingto this. A fine column of that 

 kind is in the church di S. Praffede at Rome. I 

 faw at Florence in Mr. Targioni Tozzettfs collec- 

 tion fome Tufcan lavas; which, on account of 

 their parallelopiped white merl-fpots, refembled en- 

 tirely to this Serpentine ner* antico. Mr. Cronfted 

 (Mineral 259.) fpeaks of a Serpentine antico , as 

 not being a Porphyry, but an Ophites, confiding 

 of white marble with black fteatit-cryftallizations ; 

 but I did not fee or hear at Rome of fuch an 

 antique ftone. 



3. Porfido bruno, brown, with oblong greenim 

 fpots, entirely refembling the Serpentine <verd ' an- 

 tico , the brown colour likely owing to iron-ocher. 

 There are two varieties. 



a. Liver-brown, and fair green fpots. In the 

 collection of Mr. Targioni Tozzetti at Florence ; 

 antique. 



b. Black-brown, with fpots half black and half 

 green. Count Cronftedt had bought a fpecrmen of 

 that kind. 



4. Porfdo verde. There are many fpecies ; the 



lefler 



