66 ECONOMIC GEOLOGY. 



showing very distinctly on surfaces slightly weathered. There is likewise considerable 

 included quartz. The galenite occurs in small blotches, showing a tendency to form 

 in the centre of quartz nodules. It is unusually dark-colored and splendent, plenti- 

 fully sprinkled with minute crystals of pyrites. The entire quantity of ore is slight. 



Rtimney. Upon porphyritic gneiss in the north-east part of the town is a vein 

 owned by George L. Merrill. The metalliferous mass is 12 feet wide, exposed in an 

 excavation 14 feet deep. The walls dip 80° N. 70° W., enclosing a soft feldspathic 

 rock with some quartz. Two kinds of trap rocks are situated in the vein, dark- and 

 light-colored. The galena and blende follow reticulating veins of quartz, inter-pene- 

 trating the general mass. The galena contains a trace of gold, and 1.95 oz. of silver 

 to the ton. 



North Woodstock. Handsome specimens of galena, blende, and pyrites have been 

 shown us from Horner's farm. Some work has been done in the way of opening 

 the vein. The galena shows a trace of gold, and 7.84 oz. of silver to the ton. 



Hooksett. Upon the quartz ridge south-west from the Pinnacle is a small lead vein. 

 The best part of it shows three inches width of galena. This is hardly sufficient for 

 mining. 



Other localities are in Bath, Haverhill, Epsom, Nashua, Lyndeborough, Dunbarton, 

 Tamworth, Sandwich, Lyme, and elsewhere. 



Tin. 



Tin ore has been discovered in Jackson in such quantity and so re- 

 lated that miners have thought a good vein of it might be developed by 

 diligent exploitation. From time to time prospectors have searched the 

 neighborhood, particularly in Maine, where greater success has been met 

 with than in our state. Dr. Jackson was greatly interested in the sub- 

 ject, particularly as this was the first discovery of the ore in so great 

 quantity in the country. From investigations made about 1840, the 

 following conclusions have been derived: 



The rock of the country is a mica schist dipping 30° N. E. by E., with veins or 

 elvans of granite crossing it. The ore is cassiterite, occurring in four veins, making a 

 triangular space of 200 to 300 square feet by their intersection. No. i is mostly com- 

 pact ore, eight inches in the widest part, yielding 30 per cent, of tin, associated with 

 chalcopyrite and mispickcl, and the course is N. 7° E. No. 2 contains crystalline ore 

 with mispickcl, half an inch wide, running N. 80° E. in granite. This ore crosses 

 the others, like the horizontal line in a figure 4. No. 3 is a compact ore in mica 

 schist, from half to three quarters of an inch wide, running N. 56° E. No. 4 is nearly 

 parallel to the last, from a half to an inch and a quarter wide. No. i is cut by a dyke 

 of trap. The rock near the veins contains from two to ten per cent, of tin. The 

 other minerals found with the cassiterite are mispickcl, pharmacosiderite, chalcopyrite, 



