i899 H. WINWOOD— CARRARA QUARRIES 69 



mineral molecules under the influence of chemical 

 decomposition, might account for this alteration. Stefani 

 does not agree with the view that the formation of the 

 marbles is due to compression, but attributes the altera- 

 tion to slow molecular changes, brought about by 

 circulating waters and by the ordinary metamorphic sur- 

 roundings. (Geol. Mag., 1890, p. 373.)* 



It might be interesting to give an analysisf of the marble, 

 which is almost pure Carbonate of Lime : — 



Carb. of Lime 98' i 

 Do. Magnesia 09 

 Clay and quartz 10 



1000 1000 



There are crystals of calcite, iron pyrites, gypsum, 

 sulphur, and pure white rhombohadral crystals of dolo- 

 mite. In the cavities of the best marble clear quartz 

 crystals called " Madre macchie " and " Carrara diamonds," 

 sometimes one inch long and pointed at both ends, occur, 

 and are much sought after. 



Method of Working 



In conclusion, a few words may be written on the 

 methods of working and conveying the blocks from the 

 difl'erent quarries. The w^ay in which the vast mass of 

 debris is shot from one slope to another at the discretion 

 of the many proprietors, without any organised system, is 



* We need not go far to see an alteration in limestone rocks obliterating their 

 ordinary lithic features. A visit either to the fields around Castle Comfort, on the 

 Mendips, or to Shepton Mallet, will afford very good instances. Scientists have not yet 

 succeeded in showing cause for this metamorphism, neither do they agree as to that of the 

 limestone of the Apuan Alps. 



t Berthier (T. des essais, toni, i, p. 614). 



