115 



neither numerous nor very good ; the best comes from the 

 Aroa mines, the small granular pyrites appears to be most 

 abundant in a decomposing gneissoze rock. 



The galenas are from mines at Los Teques, Aroa, and 

 Campano, several are pseudomorphous crystals in filmy 

 aggregations, interesting specimens for the mineralogist. 



The iron ores include specimens of pyrites (mundic) which 

 in Venezuela appears to be as abundant as in most palaeozoic 

 regions, ten of the samples are rich, and would be profit- 

 able if the cost of mining is not too expensive at Barquis- 

 imeto, Caracas, and the Aroa mines. 



The haematites include specular, micaceous, and red u'on 

 ores, all comparable to the best European ores. The lim- 

 nites comprise bog-iron ore of recent formation and a brown 

 amorphous ore. The siderites include an aggregation of 

 tabular crystals from Caracas, probably a carbonate of 

 protoxide of iron valuable in making steel, and massive 

 clay ironstones from the districts of Corui Machate, where 

 coal is also worked. The crystallised and compact magnet- 

 ites come from the same place. A thin vein of brown 

 siliceous ironstone has its surfaces covered with minute 

 fragments of clear quartz, singular and beautiful under the 

 microscope. 



The carbonaceous minerals are coals, graphite, sulphur, 

 asphaltum and -petroleum. The coals are from Nuevo Mundo, 

 where Mr. Spence has proved the existence of workable 

 coals, the Island of Toas in the Lake Maraciabo, and a can- 

 nel coal from Coro, with several black shales from these 

 localities. These coals are undoubtedly of excellent quality, 

 and from report can be worked economically ; their age is 

 at present unknown from the want of any proper geological 

 survey, and in the absence of fossils of any kind in the 

 shales in this collection; in all probability however the 

 Venezuelan coals are of true carboniferous age. 



- The graphite from Caracas is an impure amorphous earthy 



