TOURMALINE. 189 



3.) The electric polarity of the crystals, when heated, is 

 another remarkable character of this mineral. 



Obs. Tourmalines are common in granite, gneiss, mica 

 slate, chlorite slate, steatite, and granular limestone. They 

 usually occur penetrating the gangue. The black crystals 

 are often highly polished and at times a foot in length, though 

 perhaps of no larger dimensions than a pipe-stem, or even 

 more slender. This mineral has also been observed in 

 sandstones near basaltic or trap dikes. 



Red and green tourmalines, over an inch in diameter and 

 transparent, have been obtained at Paris, Me., besides pink 

 and blue crystals. These several varieties occur also, of less 

 beauty, at Chesterfield and Goshen, Mass. Good black tour- 

 malines are found at Norwich, New Braintree, and Carlisle, 

 Mass. ; Alsted, Acworth, and Saddleback Mountain, N. H. ; 

 Jladdam, Conn. ; Saratoga and Edenville, N. Y. ; Franklin 

 and Newton, N. J. 



Dark brown tourmalines are obtained at Orford, N. H. ; in 

 thin black crystals in mica at Grafton, N. H. ; Monroe, Ct. ; 

 Gouverneur and Amity, N. Y. ; Franklin and Newton, N. 

 J. A fine cinnamon brown variety occurs at Kingsbridge, 

 Amity, and also south in New Jersey. A gray or bluish- 

 gray and green variety occurs near Edenville. 



The word tourmaline is a corruption of the name in Ceylon, 

 whence it was first brought to Europe. Lyncurium is sup- 

 posed to be the ancient name for common tourmaline ; and 

 the red variety was probably called hyacinth. 



Uses. The red tourmalines, when transparent and free 

 from cracks, such as have been obtained at Paris, Me., are 

 of great value and afford gems of remarkable beauty. They 

 have all the richness of color and luster belonging to the 

 ruby, though measuring an inch across. A Siberian speci- 

 men of this variety, now in the British museum, is valued at 

 £500. The yellow tourmaline, from Ceylon is but little in- 

 ferior to the real topaz, and is often sold for that gem. The 

 green specimens, when clear and fine, are also valuable for 

 gems. A stone measuring 6 lines by 4, of a deep green 

 color, is valued at Paris at $15 to $20. The thin crystals 

 of Grafton, N. H. are transparent, and may be used as sug- 

 gested by B. Silliman, Jr., in polarizing instruments. 



Where have fine specimens of red and green tourmaline been found 

 in the United States 1 What is said of yellow tourmaline ? What if 

 the value of tourmaline as a gem 1 



