TOURMALINE. 



Early in the eighteenth century some 

 children of Holland, playing on a warm 

 summer's day in a court yard with a few 

 bright colored stones, noticed that these 

 possessed a strange power when warmed 

 by the heat of the sun. They attracted 

 and held (just as a magnet attracts iron) 

 ashes, straws and bits of paper. On re- 

 porting this strange discovery to their 

 parents the latter, it is said, could give 

 no explanation of the curious property, 

 but a relic of their knowledge of it is 

 left in the name of "aschentreckers" or 

 "ash-drawers" which they gave the 

 stones and by which they were known for 

 a long time. 



Such was the method of introduction 

 to the civilized world of the mineral now 

 known as Tourmaline, a mineral which 

 in variety of color, composition and prop- 

 erties is one of the most interesting in 

 Nature. 



The lapidaries who had given the 

 Dutch children the stones for playthings 

 did not recognize them as different from 

 the other gems in which they were ac- 

 customed to deal. So to the present day, 

 although Tourmaline is considerably used 

 in jewelry, it is rarely ever called by that 

 name. The green varieties are often 

 known as Brazilian Emerald, Chrysolite 

 or Peridot, some varieties of blue as Bra- 

 zilian Sapphire, others as Indicolite, the 

 colorless as Achroite, and the red as Ru- 

 bellite, Siberite, and even as Ruby. 



It is only somewhat recently that these 

 different stones have been recognized as 

 being varieties of a single mineral spe- 

 cies which is known by the name Tour- 

 maline. This name comes from a Cinga- 

 lese word (turamali) which was applied 

 to the first Tourmaline gems sent from 

 Ceyon to- Holland. 



At one time the name Schorl was 

 chiefly applied to the species. This was 

 before the means of distinguishing min- 

 eral species were as well understood as 



they are now, and a large number of min- 

 erals and even rocks were included under 

 the name Schorl. One by one, however, 

 they were distinguished by separate 

 names until Schorl included only Tour- 

 maline, and shortly afterward the name 

 Schorl was dropped altogether. 



In its opaque form, colored either black 

 or brown, Tourmaline is a comparatively 

 common mineral. It accompanies many 

 so-called metamorphic rocks, i. e., rocks 

 which have been changed by heat and 

 pressure from their original condition, 

 and is also common in granite and other 

 eruptive rocks. As a rock forming min- 

 eral it often occurs as long, slender 

 prisms, frequently about the size of a 

 darning needle and radiating in all direc- 

 tions. The only mineral for which it is 

 likely to be mistaken in this form is 

 Hornblende. It can be distinguished from 

 this in the following manner : On fusing 

 the powdered mineral with a mixture of 

 bisulphate of potash and fluor spar (best 

 done on a little loop of platinum wire) 

 Tourmaline will color the flame green, 

 while Hornblende will produce no col- 

 oration. 



The black opaque crystals often reach 

 a large size, as some are known to be 

 four feet in length. Both black and 

 brown Tourmaline are usually opaque, 

 and hence have no value as gems. The 

 Tourmalines available for gems are trans- 

 parent and have a great variety of color. 



The gem Tourmalines are to be found 

 in only a few localities. They occur in 

 Maine, Connecticut and California in our 

 own country, and also in Brazil, Russia 

 and Ceylon. The crystals are usually in 

 the form of long, slender prisms. They 

 often have the peculiarity of being differ- 

 ently colored in different portions. Thus 

 a crystal may be green at one end and 

 red at the other, and in cross section may 

 show a blue center, then a colorless zone, 

 then one of red and then one of green. 



74 



