ANNIVERSARY ADDRESS. 43 



he says, the ore of iron, with Chrome, presents masses more or less 

 voluminous, but commonly of the size of one's head. In some 

 places there are heaps of these lumps, some cubic metres in 

 volume. These are explained by the natives as piled up to be 

 used as veritable shot in a contest with the natives of the Isles 

 of Pines and Ouen, who came to ravage the plains of Marari 

 and Boulari. On the east side of the south-eastern extremity 

 of Mont d'Or there is a mass of crystalline chrome ore, and 

 descending towards Khouen a series of chrome ores is met with. 

 This mineral is found in nodules in the Steaschists of Balade, to 

 the north-east ; in crystalline grains in the serpentine schists of 

 the south and of the north-west; in crystals more or less 

 voluminous in the diallagic serpentines — the diallages, the ores 

 of iron of the south ; in amorphous masses, also, and in heaps 

 more or less considerable in the clays in the midst of the serpen- 

 tines. Lastly, chromate of iron composes almost exclusively 

 the metalliferous black sands which cover the banks throughout 

 the south of the Island and the beds of the rivulets which circu- 

 late in the serpentines. Among all the modes of deposit of the 

 chromate of iron, there is only one which presents this ore in 

 such abundance and purity for remunerative working as that 

 where it shows itself in heaps amidst the serpentines, and which 

 we find in Mont d'Or. Everywhere in traverses of the moun- 

 tain he met these heaps more or less. 



He calculates that the cost per ton of this ore from the quarry 

 to France will be something under 12 francs, or 10s. He then 

 gives the mean of two analyses of the chromate of iron, of 

 which one was made at the School of Mines of Saint-Etienne : — ■ 



Peroxide of iron 34-000 



Sesquioxide of chrome 61'333 



Alumina 0114 



Magnesia 0*012 



Silica 4-625 



Loss, &c 0*016 



100-100 



