go ECONOMIC GEOLOGY. 
two great areas of porphyritic gneiss. Those who search for this min- 
eral will find that the valuable deposits of mica are to be found chiefly 
within this fibrolite area as delineated upon the map, corresponding with 
that of the feldspar. 
Quarries for mining mica have been opened in the following localities: 
In Grafton, the oldest and best known establishment is that of the Rug- 
gles company, upon Isinglass hill. About 1840 they obtained some 600 
or 700 pounds annually, valued at $1,500. In 1869 they marketed 75 
boxes of 350 pounds each, worth from $2.15 to $2.50 per pound. This 
makes a total of 26,250 pounds, worth perhaps $60,000. In January, 
1877, the Ruggles mine is said to have shipped 3,600 pounds of mica, 
selling for $2 per pound. They employed, in 1869, 12 men for seven 
months of the year. Within two or three years the price of mica has 
increased, and hence the business has been much stimulated. Grafton 
now has six openings, which are all worked. Mellen’s quarry is about 700 
feet above the valley, to the north of the Ruggles mine. There are six 
or eight places where excavations have been made. Martin & Page are 
at work energetically, near the top of Alger or Beryl hill. This is the 
locality where the largest known beryl was once on exhibition. These 
parties have worked here for two years. Another place is opened by 
Kilton & Sargent. On Hoyt hill in Orange is the Worcester mine. The 
vein shows for 400 or 500 feet near the hill-top, and its maximum width 
is 100 feet. Five men were employed here at the time of my visit. The 
largest plate of mica obtained here is 8 inches square. There are two 
other mines on the east side of the railroad in Grafton. There are others, 
in Alexandria, New Hampton, Wilmot, Marlborough, Acworth, Alstead, 
Groton, and Springfield. The Alstead quarry has been worked intermit- 
tently the past thirty years by Mr. James Bowers, who sold in 1840 one 
thousand dollars’ worth to the Boston market. His quarry is on Beryl 
hill, a famous locality for the latter mineral. On Hall’s farm in Groton 
are unusually large plates of mica, where no mining has been done. The 
Springfield locality has furnished beautiful and large tourmalines. 
Those who drive about Springfield, Grafton, Orange, etc., cannot fail to 
see these veins on the hill-tops, whitening their crests and sides. The 
vein on Hoyt hill, Orange, is quite conspicuous on the right-hand side, 
as the cars near the summit from the south. Aaron’s ledge in Spring- 
