92 W. P. Headden — Columbite and Tantalite. 



The smaller crystals are more highly modified than the larger 

 ones, as the following readings show. Both crystals here given 

 are from the Etta mine. The forms observed are : 001, 061, 

 031, 032, 010, 110, 130, 100, 122, 132, 102, 131, 101(?), Ill (?)'. 

 A fragment of a small and very bright crystal gave the follow- 

 ing : 001, 031, 032, 010, one prism, probably 130, a brachy- 

 pyramid 122(?), 102, 113. The larger crystals are much simpler, 

 the usual forms being 001, 031, 010 and 100. The crystals 

 from the unknown locality have a rather strong luster on all 

 surfaces, and 010 is strongly striated, due to polysynthetic crys- 

 tallization. The macrodomes are wanting, and the other sur- 

 faces are 110, 100, 162(?), 102, 131, 001. The crystals from the 

 Advance claims have a different habit, being prismatic* 



The occurrence of columbite in the northern Hills is con- 

 fined, so far as known, to the stream-tin and to the three claims, 

 the Centennial, the Uncle Sam and the Yolo. The crystals 

 from the stream-tin are either tabular or stout prismatic in 

 habit with quadrangular sections. Those from the Centennial 

 claim are bright tabular crystals resembling those from the 

 Etta mine ; the few small crystals obtained from the Yolo claim 

 show only the three pinacoids. The mineral is not abundant 

 in this section, neither of those claims having furnished more 

 than a few pounds of it. 



My specimens from the stream- tin came from Mallory and 

 Upper Bear gulches ; for the former I am indebted to Mr. 

 Mark Hydliff, for the latter to Capt. St. John, both of Bear 

 Gulch. The columbite from Mallory Gulch and from the Yolo 

 mine is different from that of the southern Hills, and also from 

 that found on the Centennial claim. The latter occurs in an 

 intimate mixture of albite and quartz, and forms black, shining 

 tabular crystals, while the Yolo mineral occurs in irregular 

 masses in a mixture of albite, quartz and muscovite. Its color 

 is dark gray rather than black, and the small plates of mica 

 adhere to it, forming a kind of coating. These masses and the 

 only tabular crystals which I have definitely recognized, have 

 been broken and the parts moved past one another ; the parts 

 correspond perfectly, and the space between them is filled indif- 

 ferently with quartz, fine granular albite or mica, according to 

 the nature of the adjacent mass, which shows the order of their 

 separation and the igneous character of the vein. 



Method of analysis. — The mineral was decomposed by fusion 

 with potassic hydric sulphate; the fused mass powdered and 

 boiled out with water, at least twice, and the mixed acids 

 digested with ammonic sulphide to remove any stannic and 

 tungstic oxides. I found Blomstrand's objection to fusion with 

 sodic carbonate and sulphur, i. e., that some of the acids go into 

 solution fully justified. The ferrous sulphide was dissolved 



