245 



Carbonate of lime, 97.9 



Carbonate of Manganese and Iron, - - - 1,8 



Insoluble Silica, 0.3 



100.0 



It does not contain any majjnesia, a remarkable fact, consider- 

 ing its close contiguity to the Dolomite. 



Dr. Jackson stated he had on this same excursion 

 examined a remarkable locality of Iron Ore, near 

 Whitehall station on the Northern Central Railroad, 

 about 20 miles north of Baltimore. 



This locality presented some interesting geological and miner- 

 alogical phenomena. The rocks were Talcose rock or soapstone, 

 chlorite slate, and masses of crystallized garnets so closely packed 

 together in chlorite as to resemble a pudding stone in general ap- 

 pearance. The garnets are regular rhombic dodecahedrons, and 

 are generally of the size of grape shot, tliough some of them are 

 as large as a turkey's egg. The chlorite slate is filled with an 

 impurity of crystals of octahedral magnetic iron ore, and with 

 veins of the granular ore of the same kind. The soapstone gen- 

 erally underlies the iron ore, though it alternates with the chlorite 

 slate in one instance at this mine. The iron ore with the chlorite 

 slate and garnet rock are mined together, and the ore sells at a 

 neighboring anthracite furnace at $3 per ton. Dr. Jackson said 

 that no one would, on looking at the heaps of this ore, conceive it 

 worth any thing for furnace purposes, but on analysis he found 

 that an average sample of the ore yielded 41 per cent, of the per 

 oxide of iron, which is equal to 28jo per cent of metallic iron. 



A certain proportion of garnets aids the smelting of the iron 

 ore by their ready fusion and by preventing the absorption of any 

 oxide of iron by the slag even if the garnet itself does not yield, 

 as it probably does, a certain proportion of iron in the smelting 

 furnace. 



Dr. C. T. Jackson presented, in the name of W. E. S. 

 Whitman, Esq., of Gardiner, Me., specimens of the 

 shells, [Alasmodonta arcuata) which are opened for pearls 

 in that State. 



