132 M. B. Lewy's Expedition to New Granada. 



Among a number of the more interesting observations of 

 Mr Lewy, which are illustrated by the specimens in the 

 museum, are those which refer to the celebrated emerald 

 mine of Muzo. 



The repositories of the emeralds are situate in the middle 

 of a formation of black carburetted limestone. They are 

 accompanied with crystals of calcareous spar and of paricite. 

 As Mr Lewy collected in the same limestone of Muzo. and 

 at a considerable depth, species of ammonite peculiar to the 

 Neocomien series, he appears to have established the re- 

 markable fact that the repository of the emeralds in Muzo 

 is situate in unaltered Neocomien deposits. 



Examined in a mineralogical point of view, the specimens 

 consist of, — 



1. Crystals of emerald and Paricite (carbonate of Lan- 

 thanium), from the mine of Muzo ; 



2. Native gold, from the mines of Antioquia ; 



3. Red silver and sulphuret of silver, from the mines of 

 Santa Anna; 



4. Fer oxydule, and iron pyrites, from Patcho ; 



5. Ores of copper, from Moniquira ; 



6. Different specimens of black compact limestone ; many 

 are crystalline and exhibit the lamellar texture. 



The external characters of the last mentioned limestones 

 do not enable us to judge of the period of their geological 

 formation. But one of the specimens which contained crys- 

 tals of sulphur, bore a strong resemblance to the limestone 

 of Saliez in the Pyrenees, and that of Conil in Spain ; 

 both of which belong to the lower part of the cretaceous for- 

 mations. The position of Palma from whence this limestone 

 came, a little above Muzo, is in accordance with the presence 

 of the crystals of sulphur, and which proves the identity 

 of this crystalline limestone with the Neocomien series. 



M. Dufrenoy, in studying on the beautiful map of New 

 Granada, by Colonel De Costa, the position of the different 

 minerals collected by Mr Lewy, concludes that these mine- 

 rals form two distinct groups of formation, viz., 1. The black 

 limestone of Muzo, the crystalline limestone of Palma, the 

 schists of Moniquira, the pyrites of Velez, belonging to the 



