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Gibbs on Tourmalines, &c. yo a 
The tourmaline is found of almost every chan and this 2% 
variety of color caused at first a number to be formed into 
new es a are now considered only as varieties of 
the tourmaline: such as the rubellite, the tourmaline apyre, 
and indicolite. . ; . —. 
_ The different analyses of the tourmaline, however, affords a 
greater variety of results than is known in almost any other 
mineral. 
The amercite gravity of the black varies from 3.08 to 3.36 
reen from 3.15 to 3.10 
Red from 2.87 to 3.10 
Analysis gives Silexfrom - - - - 35to 58 
Alumine - - - - = 20 to 48 
Magnesia - -, = = Oto10 — 
Iron - + = © = = OW20 
Manganese - - = - 0 to 13 
Alkali ee ee = Oho 10 
Water 3 Ses Oe 
These differences must be in some measure ascribed to a 
defect in the accuracy of some of the analyses. But it appears 
that iron has not been discovered in the red tourmaline. It is 
hot unworthy of notice, that the red tourmaline is considered 
a8 infusible but the others as fusible. 
The red tourmaline has been the most valued, from its 
Scarcity, its employment in jewelry, and the beauty of its 
crystals. It has been discovered in Siberia, in Moravia, in 
the East Indies, and in Massachusetts. In Siberia it is found 
ina vein of decomposed feldspar ina fine grained-granite, with 
black tourmaline. In Moravia with quartz and_lepidolite (or 
rose-colored mica) in gneiss. In the East Indies, at Ava and 
Ceylon, but its geological situation is not known, though it is 
Probably in gneiss or granite. 
Could not determine. He ue devoted a long life to the improvement of sci- 
€nee; and it is his praise, that 1 the meekness of religion amidst 
the most flattering success. ae scientific countrymen, who have visited Paris, 
have been particularly indebted to him; and this notice is, in their behalf, both 
the tribute of justice and gratitude. 
