MINERALS OF MARYLAND. 113 



of the Monocacy river, consists of transition argiilite, em- 

 bracing as subordinate rocks, a variegated silico-magnesian 

 iiniestone, quartz rock, compact hornblend rock, and old red 

 sandstone in its north-western part. Its minerals are 



Sulphiirel of copper^ (pure.) 



Carbonate of copper ^ (large and fine specimens.) 



Pyritous copper. 



Sulphiiret of lead. 



Specular oxide of iron. 



Oxide of manganese. 



Carbonate of Ihne in crystals. 



Sulphate of baryta. 



Quartz in crystals. 



Extensive quarries of roofing slate are opened in various 

 parts of this district east of the Monocacy, and some of it is 

 well adapted to its appropriate use. There is also an in- 

 durated slate, which is easily wrought, resists the action of the 

 weather so as to be used for tombstones and building. 



The copper ores, consisting principally of the carbonate and 

 pure sulphuret, exhibit very favourable surface indications, iw. 

 numerous localities between the villages of Newmarket and 

 Taney town, and are always associated with the variegated 

 limestone, which is not a continuous formation, but consists 

 of isolated masses (without appearance of stratification) em- 

 braced by the argiilite ; in one spot a spherical mass about 

 forty feet in diameter, was completely enveloped by the slate 

 and its existence only known in consequence of an excavation 

 having been made for a road. Althougli the copper ores are 

 associated with the limestone, yet thus far it appears to be 

 most abundant in the adjacent slates. It does not appear in 

 the mining of these ores, that the true vein has been dis- 

 covered ; the ore exists in pockets, or is disseminated through 

 the rocks. The whole appearance of the region induces us to 

 think that valuable copper-mines will, at some day, be opened 

 in this part of the country. 



Sulphuret of lead exists north of the village of Liberty, but 

 has not been explored. 



Specular oxide of iron appears, scattered over the surface, 

 in masses of fifty pounds weight and less, in the vicinity of 

 15 



