Fernando di Noronha. 24!> 



made up entirely oi organic matter cemented by carbonate of 



lime, and again it contains more or K-ss sand and ashes derived 

 from the igneous rocks, and thrown up by the sea along with 

 the calcareous matter. Whore the calcareous matter is most, 



abundant and the rock is soft and easily quarried it is burnt for 

 lime, while in other places it contains too many impurities to 

 admit of it being used for such purposes. The principal 

 locality from which rock is taken for the manufacture of lime 

 •n the south side of the Bahia do Sueste (fig. 3). The 

 deposit has been extensively undermined by the water and its 

 abrupt faces display well its dune structure. The bedding 

 shows that the material must have been blown to its present 

 position from a southern or southeastern direction. Where 

 this seolian sandstone comes in contact with the igneous Tocks 

 at this place its stratification planes stand at a high angle, show- 

 ing that they were formed by the sand having been blown over 

 the top of a dune. This wind-bedded material continues 

 beneath the water line at this locality, and rises to a height of 

 forty feet or more above it. The pieces of rock used for lime 

 are taken out in flakes half an inch and more in thickress 

 and carried to the limekiln. The burning requires from three 

 to four da The lime is somewhat impure from the admix- 



ture of small fragments of igneous rocks. 



The following is an analysis* of a sample of the more porous 

 parts of this rock burned for lime. 



Analysis of specimen dried at 110°-115° Centigrade gave : 



Silica ._ 2-20 per cent. 



Alumina... _.. 0*79 " 



Ferric oxide 0*87 " 



Lime 0'27 " 



Magnesia 0*89 " 



Calcium phosphate _. 0'67 " 



Calcium carbonate 97'27 " 



Magnesium carbonate _ 049 " 



Potash 0-15 ; < 



Soda 0-22 



<; 



Total 101-72 per cent. 



Water at 110°-115° C 0-25 " 



Soluble in concentrated nitric acid 96*67 " 



Examined under the microscope this rock is found to be 

 made up entirely of triturated organic remains such as bits of 

 shells, spines and shells of sea-urchins, corals, nullipores, for- 

 aminifera, and the other calcareous growths such as cover the 



* Analyses by R. N. Bracket. 



