G. F. Kunz — Sapphires from Montana. 417 



Art. XLIV — On the Sapphires from Montana, with special 

 reference to those from Yogo Gulch in Fergus County ; by 

 George F. Kunz. 



The existence of sapphires in the State of Montana has 

 been known for some years past, and has attracted considerable 

 attention. Several localities are now known and several dis- 

 tinct modes of occurrence. They were first found in trans- 

 ported gravels along the bars of the Upper Missouri ; then 

 they have been found in the earthy product of decomposed 

 dikes, and lastly farther down in the unaltered igneous rock 

 itself ; the succession thus presents a close parallel to the his- 

 tory of the diamond-workings in South Africa. 



The first published description of the Montana sapphires 

 was by the late Dr. J. Lawrence Smith, in this Journal (III, 

 vol. vi, p. 185, September, 1873). He there said : " These 

 pebbles are found on the Missouri Kiver near its source, about 

 sixty-one miles above Benton ; they are obtained from bars on 

 the river, of which there are some four or five within a few 

 miles of each other. Considerable gold is found on these bars, 

 it having been brought down the river and lodged there ; and 

 the bars are now being worked for gold. The corundum is 

 scattered through the gravel (which is about five feet deep) 

 upon the rock bed. Occasionally it is found in the gravel and 

 upon the rock bed in the gulches, from forty to fifty feet 

 below the surface, but it is very rare in such localities." 



A fuller account of the conditions and yield was given by 

 the author in his volume on " Gems and Precious Stones of 

 North America," published in 1890 (pp. 48, 49) ; he subse- 

 quently visited the locality and examined it carefully, publish- 

 ing the results in the Appendix to the same work (pp. 340, 

 342). 



In 1891 the first serious attention began to be paid to the 

 mining of sapphires in this district. The bars consist of an 

 auriferous glacial gravel ; and in working them for gold, sap- 

 phires were obtained as a by-product. By 1890 companies 

 began to be formed and claims taken up and examined with a 

 view to sapphire-mining. The region extends for some six 

 miles along the Missouri River, the central point being Spo- 

 kane Bar, twelve miles east of the city of Helena. Other 

 names, such as Emerald Bar, Ruby Bar, French Bar, Eldorado 

 Bar, etc., were given to different points of the area. The 

 gravel rests on a slaty bed-rock and the author found min- 

 erals besides gold and sapphires ; among these are small crys- 

 tals of white topaz, garnets in rounded grains often of rich 



