294 W. P. Headden — Tantalate from So. Dakota. 



found nor learned that any sample of a tantalate was 

 f onnd at this locality, but the columbites occurring there 

 were all of high specific gravity as were all of the 

 columbites at other localities in the district. The sample 

 from Harney City, as will be seen from a later statement, 

 presents a striking case of a columbite with a high specific 

 gravity but not so extreme as the sample from Tin Moun- 

 tain in Custer Co. 



The columbites from the Old Mike Mica mine differ 

 from all the samples of this mineral that I have seen from 

 the Black Hills, in that they are of low specific gravity. 

 One sample has the lowest specific gravity that I have 

 found for this mineral from anv locality, viz. 5.201 at 

 4°C. 



The tantalate was found at the Old Mike Mica mine 

 and is, so far as my knowledge goes, the second instance 

 of the finding of this mineral in place in the Black Hills. 

 In 1889, or 1890, I found a single group of crystals at a 

 prospect hole, also in Minnehaha Gulch, 3% or more miles 

 north of Custer City. The form of these crystals was 

 subsequently determined by Prof. Penfield and found to 

 be that of tapiolite. These localities are not more than 

 three miles apart and in the same gulch. I found a tan- 

 talate of iron very sparingly present in stream-tin from 

 the Grizzly Bear Gulch and also in that from Mitchell's 

 bar, but the mineral found in these placer products may 

 really have been from the same source, as the placers 

 were only different parts of the same gulch. I supposed 

 that the source of this tantalate was the Tin Queen lode, 

 which lay above the placer working in the Grizzly Bear 

 Gulch. The Minnehaha, Sunday, and Grizzly Bear 

 gulches take their rise in the same general section and 

 the tantalate previously found may have had its source 

 farther up the gulch than I supposed, and may not have 

 had the same origin as the tin-stone, though associated 

 with it in the bed of the gulch. 



The tantalate from the Old Mike Mica mine varies 

 greatly in its specific gravity. The pieces sent were quite 

 small; the largest of them weighed between 40 and 50 

 grams, but these were not clean. The clean pieces usually 

 weighed less than 5 grams and seldom reached 10 grams. 

 Determinations of the specific gravity, made with the 

 Jolly balance, showed a variation from 6.9 to 8.0, and 



