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



Harford county possesses limestone rocks ; but it is very necessa- 

 ry that their extent and comparative value in the production of lime 

 for agricuhure, be determined correctly. She has soap stones ; and 

 her limits extend to the slate formation on the Susquehanna. Her 

 iron ores are of very rich quality. The chrome ores and magnesian 

 earths exist in abundance ; and pyritous copper, occurring with the 

 chromiferous iron ores, has been found near Cooptown. 



Baltimore county presents nearly the same mineralogical constitu- 

 tion as Harford county. Her limestone formation furnishes the great- 

 est proportion of the lime embraced in the estimate given on a pre- 

 ceding page, of the quantity annually inspected and consumed ; while 

 it is likewise extensively quarried for marble, which is obtained of a 

 fine quality for most architectural purposes, and is used also for the 

 more ordinary kinds of statuary. The mineral called graphite, which 

 is a mixture of carbon and iron, but is better known under the im- 

 proper name of blade lead, has been observed on the gunpowder. 

 Sulphuret of molybdenum, also, which yields an acid that in combi- 

 nation with the oxides of some other metals produces salts of lively 

 and permanent colors and capable of being applied in the art of dye- 

 ing and of painting on porcelain, occurs in this county, but to what 

 extent has not yet been determined. The same uncertainty rests on 

 . the occurrence of lead and q{ zinc, which has been by some confi- 

 dently asserted. 



Anne-Arundel county supplies the porphyroidal granite, now so 

 generally employed for the embellishment of Baltimore city. Sev- 

 eral localities of other varieties of this rock, which it would be super- 

 fluous to mention at present, have been observed on the line of the 

 Rail Road, along the Western branch of the Patapsco, and the de- 

 composition of that variety of the same rock known to mineralogists 

 2i% graphic granite offers, as was already stated, situations where the 

 material for the manufacture oi porcelain ware may be confidently 

 expected to occur. The limestone formation has been also ascer- 

 tained to extend through a portion of this county : and much of the 

 soap stone used in Baltimore is derived from Elk Ridge. 



Montgomery county might supply the latter article, of better qual- 

 ity, from the Patuxent ; and finally, this county, possesses, besides 

 ihe more usual concomitants of the primary rocks, a formation of 

 Manganese ore, occurring, so far as known, principally in the neigh- 

 borhood of Mechanicsville. — It has been thought, loo, that a portion 

 of this county, between Sandy spring and Rockville, presents some 



