PHYSICAL ASPECT. 



137 



ern side of the two arms — Guanabacoa and Guasa- 

 bacoa, the entire formation is de transition. Pass- 

 ing southward, we find syenite near Marimelena, 

 composed in a large degree of hornblende, and in part 

 decomposed with a little quartz, and a reddish white 

 feldspar, which is sometimes crystallized. This beau- 

 tiful syenite, whose masses incline to the north w r est, 

 alternates twice with serpentine, and the intercalated 

 strata of this stone is seventeen or eighteen feet thick. 



Further south toward Regla and Guanabacoa, 

 there is no syenite, and the entire surface is covered 

 with serpentine, in hills from 200 to 250 feet high, 

 running from east to west. This rock is much 

 fissured, its exterior being of a bluish brown color, 

 covered with detritus of manganese, and the interior 

 of leek or asparagus green traversed by small veins 

 of asbestos. It contains neither granite nor horn- 

 blende, but metallized diallage is disseminated through 

 the mass. The serpentine breaks sometimes in leaves, 

 sometimes in scales, and this was the first instance 

 of my finding metallized diallage w T ithin the tropics. 

 Many of the pieces of serpentine have magnetic 

 poles, and others have a texture so homogeneous, 

 and so firm a polish, that from a distance they may 

 be mistaken for pitchstone, (pechstein). It is desi- 

 rable that these beautiful masses should be used in 

 the arts as is done in many places in Germany. 



