108 MINERALS OF MARYLAND. 



These minerals exist in a seam of hornblend, from one to 

 four inches thick; and in the adjoining gneiss, there are 

 cavities whose surfaces are studded with crystals, mostly of 

 chabazie and zeolite, furnishing beautiful cabinet specimens. 

 The crystals of chabazie are transparent when perfect, but are 

 found in every stage of decomposition, which first renders 

 them opaque and finally they fall to powder. The crystals of 

 zeolite are transparent, and of a fine honey yellow colour; the 

 radiated variety is opaque and light yellow. 



It is much to be regretted that a disagreement between the 

 two owners of the quarry should prevent either from working 

 at this spot, which has been untouched for several years, and 

 the quarrying is not likely to be resumed. The seam ap- 

 peared to be increasing in thickness when the operations were 

 suspended. 



Sulphureis of zinc and lead were found in a small vein near 

 the locality of chabazie, but as it was not worth working, it 

 has been covered by the refiise from the quarry. 



Graphite occurs 16 miles from Baltimore, on the Gun- 

 powder, it is lamellated and very pure. 



Sulphuret of molybdenum has been met with near the last, 

 in laminated masses more than one inch broad. 



Magnetic oxide of iron occurs in small quantities in several 

 Jocaliiies. 



Titaniferous oxide of iron ox fer-titane occurs in abundance 

 in the gneiss of Harford county, and is smelted at two estab- 

 lishments. It is magnetic and possesses polarity. 



The common magnetic oxide of iron is disseminated in 

 large octahedral crystals in chlorite-slate, near the 'Rocks of 

 Deer creek,' in the same county. It also occurs in an aggre- 

 gate of chlorite and quartz, near the Forks of the Gunpowder 

 river, 25 miles north from Baltimore, and is associated with 



Pyritous copper, (in grains.) 



Sphene, in very large crystals : and 



Pycnite. 



The specular oxide of iron is very rare. 



Peroxide of manganese has been worked in Montgomery 

 county. It occurs sparingly in other places. 



The mica-slate is variously mixed up with the granite and 

 gneiss, but towards the north-western edge of the granitic range 



