315 



serpentine. The presence of water of composition in serpentine 

 materially affects its hardness, the softer varieties containing 

 the largest proportion of water. In some varieties I found as 

 much as 15 per cent., while the lowest was 7 per cent. Both 

 the Verd Antique Serpentine of Europe and of Roxbury, Ver- 

 mont, contain between 12 and 13 per cent, of water. That 

 from Proctorsville, Vt., contains but 7 per cent., and that of 

 Roxbury 13, while that from Europe contains 12.5 per cent., 

 and that of Lynnfield 15 per cent. 



Verd Antique Marble may be defined to be Serpentine mixed 

 with or containing numerous veins of magnesian carbonate of 

 lime. The relative proportions of these ingredients may vary 

 considerably on account of the isomorphic or rather plesiomorphic 

 characters of the two minerals. Carbonate of the protoxide of 

 iron, in like manner being plesiomorphic with both carbonates of 

 lime and of magnesia, replaces either of those minerals in all 

 proportions, without changing the angles of the crystals more 

 than one degree. 



It will be observed on examination of the analyses I have 

 made, that in the Vermont Serpentine the white spar veins are 

 chiefly composed of magnesite, while there are also veins con- 

 sisting of mas^nesian carbonate of lime and of carbonate of iron. 

 The relative proportions of these magnesian and ferrous carbon- 

 ates in the Vermont marble are nearly the reverse of those in 

 the European variety, thus beautifully illustrating the law of 

 isomorphous substitution of mineral ingredients. 



Owing to the refractory nature of Serpentine, and the difficult 

 erosion of the magnesite, the Vermont Verd Antique is less 

 liable to decomposition from atmospheric agencies, and also has 

 the property of resisting a high temperature, and even the action 

 of mineral and other acids far beyond the celebrated Verd An- 

 tique of Italy. When highly polished it is a rich and beautiful 

 green marble, veined with white, and sometimes is richly mottled 

 with magnesite and dolomite spar. Its polished surface is not 

 liable to erosion from atmospheric causes, and will offer no hold 

 for lichens, mosses, or other parasitic vegetation, which so fre- 

 quently mar the beauty of our more open-grained white monu- 

 mental marbles. 



