892 PHYSIOGRAPHY. CLASS 11 



they will perhaps form new genera. The description has 

 been drawn up from several not crystallised varieties from 

 Bodenmais, and the ratios of the axes of the crystalline 

 forms are those given by LEONHAJID. 



2. According to VOGEL and Count BORKOWSKY, the 

 prismatic Tantalum-ore from Bodenmais, consists of 



Oxide of Tantalum 75-00 74-00. 



Oxide of Tin 1-00 0-40. 



Oxide of Iron 17'00 20-00. 



Oxide of Manganese 5-00 4-60. 



Its chemical formula is Mn 2 Ta + 3 Fe 2 T. Upon char- 

 coal it suffers no change before the blowpipe, but it melts 

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



The Tantalite from Broddbo consists, according to BER- 

 ZELIUS, of 



Oxide of Tantalum 67-586. 

 Oxide of Manganese 5-902. 

 Oxide of Iron 7'560. 



Lime 1-504. 



Oxide of Scheelium 8-690. 

 Oxide of Tin 8-750. 



The two last of these ingredients BERZELIUS considers as 

 accidental. It is likewise unchanged by itself before the 

 blowpipe, and is slowly but perfectly soluble in borax. 



3. Prismatic Tantalum-ore is found at Bodenmais in 

 Bavaria, with rhombohedral Emerald, pyramidal Euchlore- 

 mica, rhombohedral Quartz, &c., and is said to occur there 

 in very large and distinct crystals. The variety from Had- 

 dam in Connecticut, where it is accompanied by prismatic 

 Corundum, &c., likewise belongs to the present species. 

 The other varieties occur at Finbo and Broddbo near Fah- 

 lun in Sweden, with prismatic Topaz, Albite, and rhombo- 

 hedral Quartz. In several other places in Sweden and in 

 Finland, it is imbedded in granite. 



