636 abstracts: geology 



tions at the gold and the silver-lead lodes and at the tungsten deposits 

 in 1917. 



A molybdenite-bearing quartz vein on Healy River, Alaska, which 

 has been traced by shallow openings for the length of three claims, 

 is the subject of a brief note. 



The Hot Springs district, in Alaska, has produced more than $6,000,- 

 000 in placer gold, as well as some silver and tin. Mr. Chapin describes 

 the occurrence of tin ore in the district, and gives an account of the 

 mining operations there in 191 7. Stream tin has been found in gold 

 placers in the Ruby district at several places, but not in quantities large 

 enough to pay for mining it except as an accessory to the gold. 



The Tolstoi district, Lower Yukon basin, includes an area about 12 

 miles wide by 20 miles long, which lies on the flanks of Mount Hurst 

 in the basin of Tolstoi River, on the branches of which placers that yield 

 gold and platinum have been worked for several years. The topography, 

 geology, climate, vegetation, and animal life of the district, the pro- 

 ducing placers, and the economic factors that affect mining are de- 

 scribed by Mr. Harrington. G. C. M. 



GEOLOGY. — Mineral resources of Seward Peninsula, Alaska. George 

 L. Harrington. U. S. Geol. Survey, Bull. 692-G. Pp. 48 

 (353-400), pi. I. 1 91 9. 



Stream tin has been found in many streams in Alaska, and lodes of 

 cassiterite have been prospected and mined at several places in Alaska. 

 An account of the tin deposits and tin mining in Seward Peninsula is 

 given. 



The graphite deposits of Seward Peninsula have been known for many 

 years, but gold has so long been the most valuable mineral mined there 

 that other minerals have not been much considered by the miner. 

 The location of the deposits and the work that has been done on them 

 are sketched. 



The search for the sources of the placer gold found in the streams of 

 Alaska has been a part of the work of the geologists who have been 

 studying and mapping the topography and geology of the Territory. 

 The author describes the geology and mineral resources of the Kowalik 

 and Koyuk region, stating the means of communication, timber, coal, 

 and sources of water supply, gives detailed descriptions of the gold and 

 platinum placers, and makes suggestions as to the original sources of 

 the metals. G. C. M. 



