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DESCRIPTIONS OF MINERALS. 



Axinite. 



Triclinia In acute-edged oblique rhomboidal prisms ; 



PAr = 134° 45', rA»=115° 38', Pau = 13d° 31'. Cleavage 



indistinct. Also rarely massive or lamellar. 



Color clove-brown ; differing some- 

 what in shade in three directions, being 

 trichroic. Lustre vitreous. Transpa- 

 rent to subtranslucent. Brittle. H. = 

 6-5-7. G.=3'27. Pyro-electric. 



Composition. A unisilicate, afford- 

 ing boron trioxide, and containing 

 boron among its bases. One analysis 

 afforded Silica 43*68, boron trioxide 

 5-61, alumina 15*63, iron sesquioxide 

 9-45, manganese sesquioxide 3*05, lime 

 20-92, magnesia 1*70, potash 0-64= 

 100*43. B.B. fuses easily with intum- 

 escence to a dark-green or black glass, 

 imparting a pale-green color to the 



flame, which is due to the boron. 



Diff. Remarkable for the sharp thin edges of its crystals, 



and its glassy brilliant appearance, without cleavage. The 



crystals are implanted, and not disseminated like garnet. In 



one or all of these particulars, and also in blowpipe reaction, 



it differs from any of the titanium ores. 



Obs. Occurs at St. Oristophe in Dauphiny ; at Kongs- 



berg in Xorway ; ftormark in Sweden ; Santa Maria, in 



Switzerland ; Cornwall, England ; Thum in Saxony, whence 



the name Tliummerstein and Tliumite. 

 In the United States it has been found at Phippsburg and 



\Tales in Maine ; and at Cold Spring, New York. 



Danburite, A silicate which contains, like axinite, boron trioxide. 

 Composition : Silica 48*8, boron trioxide 28o, lime 22*7. Occurs with 

 oligoclase and orthoclase in imbedded masses of a pale-yellow color, 

 at Danbury, Conn. H. = 7. G.=2-95-29G. 



Iolite. — Dichroite. Cordierite. 



_ Trimetric. In rhomlDic prisms of 120°, and in 6 and 12- 

 sided prisms. Also massive. Cleavage indistinct ; but crys- 

 tals often separable into layers parallel to the base, especially 

 after partial alteration. 



Color various shades of blue, looking often like a pale or 



