140 PHYSIOGRAPHY. 



Columbite. 



Cleavage parallel with M and T rather distinct, espe- 

 cially that of M : the cleavage parallel with P less obvious. 

 Fracture imperfectly conchoidal, uneven. Surface, M and 

 T vertically streaked. 



Lustre imperfectly metallic. Color greyish and brown- 

 ish-black. Streak dark brownish-black, on the file a little 

 shining. Opake. 



Brittle. Hardness = 6-0. Sp. gr. =6-038. 



Compound Varieties. Massive : composition granular. 



1. Upon charcoal, it suffers no change before the blow-pipe, but it 

 melts with borax, and is partly soluble in heated sulphuric acid. 



2. Analysis. 



By BERZELIUS. By VOCEL. By BORXOWSKY, 



fr. Kimito. fr.Finbo. fr.Brodbo. fr. Bodenmais. 



Columbicacid 83-2 66-99 GS-22 75-00 75-00 



Tungsticacid 00 000 6-19 0-00 0-00 



Protoxide of iron 7-2 7-06 8-80 17-50 20-00 



Protoxide of manganese 7-4 7-44 6-62 109 4-00 



Oxide of tin 0-G 16-75 8-2G 1-00 0-50 



Lime a trace. 2-40 1-19 0-00 0-00 



The Columbite of Chesterfield, (Mass.) consists of the oxides of co- 

 Juiiibium, tin, iron and manganese, with a trace of lime. 



3. Columbite occurs in granite veins, usually attended by Beryl. 



4. It is found at Bodenmais in Bavaria, associated with Beryl and 

 Uranite, where it exists in very distinct crystals. Also at Finbo and 

 Brodbo near Fahlun in Sweden, with Topaz, Albite, and Quartz. It 

 has been met with at several other places in Sweden and Finland. 



Columbite was first discovered near New London, (Conn.) and- the 

 specimens sent by Gov. Winthrop to Sir Hans Sloane. The original lo- 

 cality has never since been re-discovered ; but the mineral was subse- 

 quently found at Haddamin the well known Chrysoberyl deposit, which 

 place still affords fine specimens of it, though in very limited quantity. 

 More distinct crystals, arid of greater magnitude, come from Chester- 

 field, (Mass.) where it exists along with variously colored Tourmalines 

 and Beryl in granite. The most perfect crystals, as well as the largest 



