22 Localities of Minerals in Massachusetts. 



Oxide of Manganese. 



The siliceous oxide of manganese exists in Curtiming- 

 ton in immense quantity lying in bowlders in the stone 

 walls, half a mile west of the congregational meeting- 

 house, on the farm of Mr. Packard. The masses vary 

 from a few inches to several feet in diameter, and are uni- 

 formly of a coal black on their surface, being covered with 

 the compact oxide of manganese, from a mere line to two 

 or three inches in thickness. On breaking open these un- 

 sightly masses, the interior is disclosed of a beautiful rose 

 red, sometimes imperfectly, sometimes distinctly, foliated, 

 and much resembling rose quartz, except in being of a 

 deeper colour. I doubt not it would be an easy matter to 

 collect at this locality fifty tons of this mineral ; so that 

 there is no danger of its being exhausted. I could not 

 find the ores in place, though from the appearance of some 

 specimens I have little doubt they form a bed in mica-slate. 



Is not the fact that the masses of this siliceous oxide of 

 manganese, at this locality, are always covered with a coat- 

 ing of the compact oxide, vvordiy of the notice of the min- 

 eralogist .'' Does it not lead to the conclusion, that the latter is 

 produced by the action of the atmosphere upon the former.'' 

 Veins of the compact oxide do indeed penetrate to the centre 

 of the masses ; but they appear uniformly to follow cracks, or 

 interstices, into which the air had penetrated. Mr. Bryant, 

 who lives near the spot, pointed out to me a specimen, 

 which had been broken a year or two since, and which, by 

 simple exposure to the weather since that time, had alrea- 

 dy become coated by a thin pellicle of the black oxide. 



Carbonate of Iron. 



This mineral, as might be expected, occurs at the same 

 locality ; but I did not notice much of it. Its colours are 

 , pale yellow, passing to brown, reddish brown, and even 

 blackish brown. It occurs in laminated masses, not large, 

 and perhaps passes into brown spar. Carbonate of Iroa 

 is found also in abundance in Plymouth, Vermont. 



