Report on the projected Survey of the State of Maryland. 23 



The more important veins of the ore, so ffir discovered in the last 

 named locality, are in limestone. They consist principally of that 

 variety called the sulphuret of copper, which is known to be the best 

 of copper ores; for it requires but two simple operations to reduce 

 it to the metallic state ; whereas the English and South American 

 ores require from eighteen to twenty distinct meltings. The veins 

 have been pursued with great industry to a considerable extent, and 

 ore to the amount of several hundreds of tons has been extracted 

 from them. But, notwithstanding the judgment displayed by the pro- 

 prietors of the mine so long as the works were in operation, the un- 

 dersigned are of opinion, from a careful examination of the spot and 

 of the surrounding country, that operations have thus far been carried 

 on in straggling veins only ; while the main body of the ore, whose 

 existence is hardly to be doubted, has not yet been reached. 



The only application, at present, made of the mineral resources of 

 this spot is to produce a sulphate of copper. This salt, the blue vit- 

 riol of commerce, is obtained from a material known in the country 

 by the name of black earth. It contains from 5 to 20 per cent, of 

 topper mixed with iron, manganese, and earthy matter in very varia- 

 ble proportions. It has been observed in several spots around Liber- 

 ty, appearing on the surface of the soil. The quantity of blue vitriol 

 annually manufactured from it in Baltimore, has been ascertained to 

 exceed fifty thousand pounds. 



Should subsequent researches however, as there is every reason 

 to expect, open for use the larger and more convenient deposites of 

 copper ore than those already worked, another object of application 

 is already at hand from which almost incalculable wealth might be 

 reasonably supposed to accrue to the state and to its citizens. This 

 is in the manufacture of sheet copper. Made almost exclusively 

 now of materials from South America, the Baltimore sheet copper 

 has acquired reputation in foreign countries. The undersigned need 

 not suggest how much more advantage might be realized through va- 

 rious classes of the community from a more economical material with- 

 in our own limits. 



As to the other metals that were named as occurring in this region 

 of Frederick county, the iron ore observed in the vicinity of New 

 London, has been found to be of that variety called specular oxide 

 of iron, generally considered as a valuable and profitable ore, and 

 yielding iron of excellent quality. The occurrence of lead was dis- 

 covered some years back at Unionville, in a vein of galena running 



