NATURAL HISTORY OF AFRICA. 
429 
Serpentine. 
This green coloured mountain rock occurs in beds 
in the mountains to the west of the Nile, where it 
is associated beds with limestone and clay slate ; also 
along with clay slate and beds of compact felspar 
in the mountains that range along the west side 
of the Red Sea. It is erroneously described by 
some authors as a green coloured marble. 
Marble, or Granular foliated Limestone* 
Beds of this rock of a white, grey, yellow, bluish, 
and red colour occur, in beds with clay slate, and 
also with serpentine, in Upper Egypt, Darfur, and 
Abyssinia. In these countries it is occasionally 
intermixed with serpentine, forming the well 
known compound rock named verde antico. 
Greywacke, named also Breccia di Verde. 
This conglomerated looking transition rock oc- 
curs in beds of great thickness and extent, along 
with clay slate in the ranges of mountains that ex- 
tend towards Cosseir. It is remarked, that as we 
approach Cosseir, three sets of rocks succeed each 
other : the first set is small, granular, and granitic j 
the second set is of the breccia di verde; and 
the third of slate, which alternates with and passes 
into the breccia. 
