246 



oxide of iron have resulted from the decomposition of the car- 

 bonate of iron in the Ankerite. Volcanoes, we know, do give 

 out abundant fumes of peroxide of iron, which crystallizes as 

 specular iron ore in the volcanic cavern. May not a subaqueous 

 eruption have produced the pulverulent peroxide abounding in 

 these mines ? Atmospheric causes do not appear to have been 

 adequate to the decomposition of such enormous quantity of 

 Ankerite, as would be required to yield so much of the per- 

 oxide. There are small veins, bunches, and films of black oxide 

 of manganese in these ores of iron, and this renders them more 

 particularly valuable in the production of steel, since it has been 

 discovered that an alloy of metallic manganese with iron is 

 highly useful in the production of the finest steel, such as the 

 iron from this ore is known to produce. 



Since my return home, I have made chemical analyses of the 

 ores of these mines, and have obtained the following results. 

 Specimens of the Ankerite yielded on analysis : — 



No. 1 Yellow Ore No. 2 Brown Ore 



-^•45) . . 20.30 

 0.80 j 



44.80 . . 49.20 



30.80 . . 30.20 



0.10 



Carbonate of Iron 

 Carbonate of Manganese 

 Carbonate of Lime 

 Carbonate of Magnesia 

 Silex .... 



99.95 99.70 



This ore contains in No. 1 = 16yVo, ^"^ >" ^o. 2 = 16yV 

 per cent, of pure metallic iron. The limestone or carbonate of 

 lime in it serves perfectly for a flux in smelting the ore in the 

 blast furnace. 



An average sample made up from all the ores of the mines 

 mixed, yielded, in 100 grains : — 



Per Oxide of Iron 74.80 



Oxide of Manganese 

 Silica 



Titaniferous Iron 

 Calcareous matters . 



2.20 

 2.20 

 1.80 

 19.00 DifT. 



100.00 



