100 



W. P. Headden — Columbite and Tantalite. 



I. Hebertfs Placer, Grizzly Bear Gulch, Pennington Co., 

 S. D. Piece weighed 2*5 grams. II. Same locality, fragment 

 not so large as preceding. III. Same locality, weight of sam- 

 ple 2 grams. IY. Coosa Co., Ala., specimen bought of Messrs. 

 Ward & Howell, Rochester. Weight 3 grams ; color black, 

 streak brown. The surface was quite regularly and deeply 

 pitted. 



Tantalite. 

 i. ir. nr. iy. 



Sp. Grav. 7-773 7'789 8*200 



Ta 2 5 78-20 78'35 82-23 71-37 



0b 2 O 5 6-23 6-24 3-57 8-78 



Sn0 2 0-68 0-58 0'32 5-38 



FeO 14-00 14-05 12-67 8-44 



MnO 0-81 1-14 1-33 5'37 



99-92 100-36 100-12 99-34 



lgn. 0-20 deducted. 

 Atom. Equiv. 



Ta 2 5 .- .35-23 35-29 37-05 32-15 



Cb 2 5 4-65 4-66 2'66 6'55 



Sn0 2 0-45 0-38 0-21 3-58 



40-33 40-33 39-92 42-28 



FeO 19-44 19'48 1779 11-71 



MnO. 1-14 1-60 1-59 7'56 



20-58 21-08 19-38 19-27 



Atom. Ratio. 



Ta:Cb 8:1 8:1 14:1 5:1 



I have found several fragments of crystals showing surfaces, 

 and one crystal was sufficiently well preserved to enable me to 

 recognize the habit of the mineral and the following surfaces : 

 001, strongly etched, two pyramidal surfaces very poorly 

 developed and one prism ; the sp. gr. of this crystal is 7*212. 



These analyses, especially III, show that these tantalites are 

 poor in columbic acid and manganese. It is remarkable that 

 this should be so, as the columbites of our localities are charac- 

 terized by a large and often predominating portion of the latter. 



I have also found two small specimens of tantalite in the 

 stream tin from Mitchell's Bar, a locality about one and a half 

 miles north by east from the Etta Mine, but no analyses have 

 yet been made of them. 



3. Manganese Columbite. 



The mineral described in this note occurs on the Advance 

 Claim, one of the Dixie group of tin mines, on Elk Creek 

 about one and a half miles south of the Etta mine, Penning- 

 ton Co., S. D. It occurs in a vein of granite which apparently 

 folds over the crest of the hill ; its thickness was not measured 



