68 MINERALOGY AND LITHOLOGY. 



Millsfield, Groton, and Warren, are localities. They are found at many 

 places in the White Mountains, and less noticeable crystals occur else- 

 where. The crystals obtained from the places mentioned are fine, the pre- 

 dominant color being green ; but yellow and blue crystals are also common. 

 The larger crystals are filled with impurities that make them cloudy, or 

 even white and opaque like feldspar; but often crystals are obtained which 

 are so clear, and of such a fine color, that they have been cut into gems 

 of rare beauty. The green color that predominates has been shown by 

 analysis to be due to a trace of chromium, which, when present in greater 

 amount, gives the green color to the emerald. Clear crystals, when found 

 in the quarry, are difficult to extract without producing flaws in them, 

 and hence the stones from which the most beautiful jewels have been 

 cut, have been dug up from the neighboring soil, where they were depos- 

 ited by being washed out from the decomposing granite. There is a 

 theory among the people, that by lying a long time in the soil they ac- 

 quire a heightened brilliancy. The rare beauty of these specimens is 

 rather to be attributed to the fact that they have not been subjected to 

 the jars produced by sledges and powder. 



The beryls are found in granitic veins. These veins are easily recog- 

 nized by the very large crystals of quartz, feldspar, and mica, which are 

 the constituents of ordinary granites; and the general presence of beryls 

 in them is interesting, as substantiating the theory of their formation. 

 These granitic minerals occupy large fissures, and it is thought that 

 water, which had filtered through the surrounding rocks, and which, un- 

 der a high pressure, and at a high temperature, had become saturated 

 with their soluble constituents, deposited these great crystals of the va- 

 rious minerals in these fissures, until they were finally filled with this 

 extremely coarse granitic mixture. In this way, the rarer elements, such 

 as glucinum, which exist in such minute amounts in the surrounding 

 rocks, became concentrated in these veins, forming the beryls that are so 

 common there. These veins are worked at various points, in order to 

 obtain the great crystals of mica, which are very valuable. 



Some beryls from New Hampshire have been analyzed. The analyses 

 are both made upon specimens from Acworth. The first is by Prof. C. 

 A. Joy.* The second is by M. B. Williams : f 



* Am. y. Set., ii , vol. x.xxvi, p. 91. t Geology N. H., C. T. Jackson, p. 182. 



