116 MINERALS OF MARYLANB, 



opened on the Virginia side of the Potomac, on Sleepy 

 creek. 



An impure ferruginous limestone occurs a few miles west of 

 Hancock, capable of producing a hydraulic cement, and at the 

 eastern base of Will's mountain a material is found from which 

 specimens of cement have been made, which appear to be 

 fully equal to the celebrated Parker's Roman cement in the 

 property of resisting the effects of water. 



The sixth division embraces all west of Will's mountain 

 and consists of coal mines and the old red sandstone, on which 

 they rest. The Frostburg coal region is the subject of a 

 separate paper in this volume, and the portion of the State 

 west of it has not been examined. We only know that the 

 '■great icestern coal field? embraces the western parts of Mary- 

 land. Sulphate ofharyta in nodules occurs in the Youghagany 

 river, and fine crystals of quartz are found on the Meadow 

 mountain; they are either limpid or beautifully clouded. 



Peroxide of Manganese rather ferruginous occurs a few miles 

 east of the Youghagany river. 



The browti hematitic oxide of iron has not yet been referred 

 to; it was omitted until the regions of country within our six 

 divisions had been noticed. It does not exist in the first 

 division, but occurs in independent beds, or is disseminated in 

 beds of clay or loam, resting on the rocks of all the districts 

 except the first. It occurs in many parts of Baltimore county, 

 and more particularly on the borders of the primary limestones. 

 Extensive beds of it, from 8 to 10 miles north of Baltimore, 

 furnished ore to Hampton furnace for seventy years before 

 they were exhausted, and the enhanced price of wood has 

 prevented the opening of new mines that exist in the same 

 region, of an ore that gives remarkably good metal. 



At the eastern base of the Catoctin mountain it exists in 

 abundance; but the quality of the metal is injured by the pre- 

 sence of the earthy phosphate of iron, which fills the cavities of 

 the masses of ore. It is however worked at the Catoctin fur- 

 nace and produces castings of good appearance. At this place 

 it is associated with an ore of zinc, whose oxide forms incrus- 

 tations in the upper part of the furnace, but we were unable 

 to find any distinct specimens of the zinc ore. 



