DOMAIN VII. COMPOSITE. 



NOME XXVI. LIME-STONE, WITH ACTI- 

 NOTE. 



Tirey marble. The beautiful rose-coloured marble of Tirey 

 not only contains large crystals of siderite, some- 

 times an inch and a half in length, of a black or 

 very dark green colour, bttt numerous other 

 crystals of a lighter green, which every candid 

 observer would allow to be the same substance, 

 with a slight diversity of colour. It seems now 

 to be universally allowed by the most skilful 

 mineralogists, that actinote is only a diversity of 

 siderite, with a greater portion of magnesia, an 

 earth which singularly affects the green colour. 

 But this actinote must not be confounded with 

 the epidote of Haiiy, a mistake into which many 

 writers have fallen, whereas the latter contains 

 no magnesia, and a greater quantity of lime*. 

 Under the epidote he ranks zoisite, so called 

 from Baron Zois; and the scorza, or greenish 

 sand, found near Muska, in Transylvania. The 

 sahlite he ranks under pyroxene, or augite. 

 These substances are mentioned because they 

 have been supposed to have been found in the 

 marble of Tirey, which sometimes also presents 



* See his Tableau comparatif, Paris, 1809. 8' notes 51, 55. 



