ORDER vn. RHOMBOIIEDRAL TOURMALINE.- 353 



4. In Saxony, Cornwall, and other countries, compound 

 varieties of Schorl are very frequent, but simple well pro- 

 nounced crystals are rare ; in these two countries it occurs 

 in the stream-works with ores of tin, &c. The largest and 

 most remarkable crystals of a black colour occur in Green- 

 land, in the mountain called Horlberg near Bodenmais in 

 Bavaria ; near Bovey in Devonshire in England, where they 

 are found along with rhombohedral Fluor-haloide. The red 

 varieties are brought from the government of Permia in Si- 

 beria. Less beautiful varieties of the same colour occur at 

 Rozena in Moravia, with Lepidolite in rhombohedral 

 Quartz. They were formerly called crystallized Lepidolite. 

 Of the same, and of various other, pale and dark green, 

 blue, &c., colours, rhombohedral Tourmaline occurs in 

 Quartz and Albite at Goshen and Chesterfield in Massa- 

 chusetts. Pale green crystals are engaged in the dolo- 

 mite from St Gothard, various transparent deep green, 

 red, brown, and blue colours, occur in the crystals and 

 pebbles from Brazil and Ceylon. Yellowish-brown perfect 

 crystals, imbedded in pale green prismatic Talc-mica, have 

 been lately discovered at Windisch-Kappel in Carinthia. 

 The blue varieties called Indicolite are found in the isle 

 of Uton in Sweden, where it also occurs in red and various 

 other colours. Some white specimens have been found at 

 St Gothard and in Siberia. It occurs besides in various 

 parts in Spain, France, Scotland, Norway, Piedmont, Salz- 

 burg, Tyrol, &., in more or less curious varieties. 



5. Rhombohedral Tourmaline, if fit for it on account of 

 colour and transparency, is used as a gem. The green va- 

 rieties from Brazil, formerly called Brazilian emeralds^ fetch 

 the highest price ; but they are inferior in value to real 

 emeralds. Plates of particularly the brown Tourmaline, 

 if cut parallel to the axis, absorb one of the polarized pen- 

 cils, which renders them useful instruments in the exa- 

 mination of the structure of minerals in polarized light. 



VOL n. 



