Geology and Mineralogy. 219 



No. XXXIV. Economic Series, No. 16. Limestone road 

 materials of Wisconsin ; by W. O. Hotchkiss and E. Steidtmann. 

 Pp. 137 ; 2 tigs., 41 pis. 



Bulletin No. XL1. Economic Series No. 18. A study of 

 methods of mine valuation and assessment with special reference 

 to the zinc mines of southwestern Wisconsin; by W. L. Uglow. 

 Pp. v, 73; 12 pis. 



6. Geological Survey of New Jersey, Henry B. Kummel, 

 State Geologist. — The following Bulletins have recently appeared: 

 No. 13, on Indian habitations and remains; No. 14, a Summary 

 of the State geology to accompany the geologic map; No. 15, 

 the Mineral Industry for 1913. 



7. Native Silver in Glacial Material at Columbia, Mo.; by 

 W. A. Tarr. (Communicated.) — A fragment of rock found in 

 a small ravine near Columbia, Missouri, by one of the writer's 

 students, Mr. Mayfield Kreutz, proved, upon examination, to con- 

 sist largely of argentite with an abundance of native silver. 



The specimen as originally found, was about 35x40x40 mm and 

 weighed about 30 grams. The rock is a medium-grained syenite, 

 consisting, aside from the metallic constituents, almost entirely of 

 flesh-colored orthoclase in part kaolinized and bleached in color, 

 with only an occasional, shattered grain of quartz. Disseminated 

 through the rock is a massive black mineral with metallic luster, 

 in irregular masses from several mm. across to minute specks. 

 This was found to be argentite, containing also a small amount of 

 lead, antimony, and arsenic. Intimately associated with it is the 

 native silver; it usually occurs either in the argentite, or more 

 commonly surrounding it. It also forms irregular grains in the 

 feldspar. A very small amount of native copper was detected 

 with the native silver. The silver is most abundant in the 

 bleached phase of the rock. The silver and argentite comprise 

 about 30 per cent of the rock, the argentite greatly exceeding 

 the amount of native silver, there being about 4 to 5 per cent of 

 the latter. 



Columbia, Mo. lies near the southern border of the glaciated 

 area. Only one ice-advance reached this region, that being the 

 Kansan. The fragment doubtless owes its present position to 

 this ice sheet. It might be mentioned in this connection that two 

 occurrences of native copper in the glacial material from Northern 

 Missouri have been reported to the writer. 



8. The Mineral Resources of New Mexico ; by Fayette A. 

 Jones. Pp. 77; 1 plate and map. Socorro, N. M., 1915. — The 

 state of New Mexico is noted for the variety as well as the extent 

 of its mineral productions; the value of the latter for 1914 aggre- 

 gated more than 819,000,000. It is also interesting to note that 

 gold was discovered there in 1828, copper mines were opened in 

 1804, while the turquoise workings, as is well known, go back to 

 pre-historic times. This account of the mineral resources of the 

 state is therefore of particular interest. Its value is increased 

 by the map showing the mining districts and mineral localities. 



