114 MINERALS OF MARYLAND. 



Liberty and is very abundant; the cavities are sometimes 

 lined with imperfect crystals. 



Sulphate of baryta occurs in lamellated and amorphous 



masses. 



Fine crystals of calcareous spar were obtained from one of 

 the mines, and among them I have a specimen containing 

 apparently hemitrope crystals, whose form I have not been 

 able to reconcile with the primitive form of carbonate of lime. 



Oxide of manganese is a constitu ent of a peculiar material 

 of this district ; containing black oxide of copper, peroxide of 

 iron, oxide of manganese, and earthy matters. This substance 

 is in a friable condition, and loosely fills up cavities or veins 

 in the slate. 



Crystals of quartz, usually white and more or less opaque, 

 were obtained at some of the openings. 



It is to be regretted that the mining operations have been 

 suspended; because, under judicious management, it is likely 

 the profit of the owners as well as the cause of science would 

 be promoted by their being continued. The limestone is 

 compact, and presents various shades of green, red, and 

 yellow, but the presence of silica renders it so hard, that the 

 polishing is too expensive to admit of its being brought ex- 

 tensively into use as an ornamental marble. In the northern 

 part of the range a beautiful white marble has been dis- 

 covered, which is exactly similar to the celebrated Carrara 

 marble, 



A seam of anthracite^ about two inches thick, occurs near 

 the Monocacy river, as I have been informed, but the character 

 of the rock was not stated. 



The portion of our district west of the Monocacy, consists of 

 compact blue limestone, clay slate, old red sandstone, and a 

 calcareous breccia with an earthy ferruginous cement. The 

 component masses of the latter vary in size from very minute 

 to twelve inches in thickness, and in many instances they 

 seem to have had their angles and edges rounded off by attri- 

 tion, before they were cemented together. They have a great 

 variety of colours and shades, such as brown, red, yellow, and 

 white. When polished, they have a very rich appearance, as 

 is exhibited in the columns of the representative hall, in the 

 capitol of the United States. 



