34 ECONOMIC GEOLOGY. 



properties it also occurs, but not extensively. It should always be saved, 

 as it is argentiferous, if not auriferous also. Any of the lead ores in the 

 state are likely to prove argentiferous. Such are at Warren, Shclburne, 

 Hooksett, Rumney, and Woodstock, besides recently discovered outcrops 

 in Madison. 



In this connection, I will present a brief sketch of the famous silver 

 mine of Newburyport, Mass., just over the New Hampshire line. It was 

 discovered in 1874. The high prices paid for lands in the neighborhood 

 have excited the minds of many of the inhabitants of Rockingham 

 county; and specimens of lead, pyrites, or mispickel found in that part 

 of the state have been carefully preserved, and the ledges exploited. I 

 have examined several openings in that county, as in Newmarket, Exeter, 

 Epping, Fremont, and Raymond, but have not seen anything of value. 

 The veins are of quartz, with a little pyritous ore, imbedded in one of 

 the schistose formations. The Newburyport mine is in sienite; and 

 therefore one would look for corresponding veins in the Exeter range 

 rather than the Merrimack or Rockingham groups, as many have done. 

 I looked over the Newmarket mine, and perceived that some galena had 

 been taken from it, apparently not a great amount. A dry looking quartz, 

 and considerable tourmaline like that occurring in Lebanon (see p. 104, 

 Part IV), were also observed in the opening. The Exeter range is like 

 the Newburyport rock, but parallel with it. 



The Merrimack Silver Mine, of Newburyport. 



From the reports of Prof. F. L. Vinton, made September 28, 1876, Dr. 

 R. P. Stevens's, made April 13, 1877, and the superintendent of the 

 mine, Edgar Shaw, I glean the following points of interest. Facts about 

 the history of its working, change of proprietorship, etc., are irrelevant 

 to our purpose, and will not be mentioned. The country rock is our 

 Exeter sienite. The ores occur in a vertical fissure -lode fully 200 feet 

 wide, traced two miles in a north-east-south-west course, but not of uni- 

 form thickness or value over this distance. The lode mass is compact 

 trap with quartz, seams of indurated calcareous clay and selvages of 

 softer clay, especially on the north-west wall. The ore band wrought lies 

 near this north-west or foot-wall, and consists of argentiferous galena, 

 accompanied by gray coi)pcr or tetrahedritc, with a ganguc of quartz. 



