6 EMERSON, ON MAGNETITE, &C., AT NAHANT. 



apart from the circumstance that this is the only American 

 locality known, the silicate is quite scarce elsewhere. Its foreign 

 localities are Greenland, Norway, Siberia, &c.; it is almost 

 invariably associated with elseolite, but the latter mineral often 

 occurs unaccompanied by sodalite. 



I am at present occupied with the examination of several 

 unrecognized minerals, which are disseminated in minute quan- 

 tities through the vein. From slight indications it is probable 

 that cancrinite may yet be met with; it has not been found at 

 either the old or new localities. The largest zircon that I have 

 seen measured about one-third of an inch in diameter. 



Salem, December, 1863. 



II. On Magnetite, and an Unknown Mineral at Nahaitt. 

 BY GEORGE H. EMERSON. 



( Communicated February 8, 1864. ) 



Besides the minerals mentioned by Dr. Prescott in his list, 

 communicated to the Essex County Natural History Society, 

 in the year 1839, as occurring at Nahant, I noticed, while 

 there last summer, that magnetite was abundantly disseminated 

 through the diorite near "Spouting Horn. 5 ' anl also in a simi- 

 larly constituted, but more finely grained rock, a ^ittle to the 

 West of " Pulpit Rock." In both places it is associated with 

 chalcopyrite and iron pyrites, and in both I found small, but 

 tolerably perfect, octahedral crystals, though it is, for the most 

 part, amorphous. 



A recent examination of a specimen of the greenstone from 

 the locality last named, disclosed to me a crystalline mineral 

 which I did not recognize, and whose external characters failed 

 to identify it. It was too imperfect to determine the form, or 

 even with certainty, the crystalline system to which it belonged, 

 though its cleavages, three in number, led Prof. Cooke to 

 refer it to one of the inclined systems. 



The color was a dull purple on one face, and greenish gray 

 on the other ; lustre, waxy to pearly ; streak, yellow ; hardness, 

 about that of calcite. The quantity was altogether too minute 



