Geology and Mineralogy. 385 



Bulletin No. 23 of the Geological Survey of Alabama, Eugene 

 A. Smith^ State geologist, giving statistics of the mineral 

 production of Alabama, has been compiled from the Mineral 

 Resources of the National Government. Further Bulletin No. 

 24 by George H. Clark, assistant geologist, gives an account of 

 the Alabama mica deposits. The state comes sixth among the 

 states. North Carolina furnishing about one-half that of the 

 country. 



The annual report on the mineral production of Canada in 

 1920 shows that the total value amounted to nearly $228,000,000, 

 the highest on record and an increase of 29 per cent over 1919. 

 The total value in 1886 was somewhat more than $10,000,000; 

 this was doubled in 1896 ; another decade showed further 

 increase of three and a half times, while the production now 

 noted (1920) is about three times that of 1906. For metallic 

 products the quantities obtained come in the following order : 

 copper, nickel, zinc, lead, silver, gold ; 600 crude ounces of plati- 

 num were produced. Among the non-metallic products coal 

 leads by a large amount, with gypsum and asbestos prominent. 



The second annual report for Alberta (1920, 152 pp.) has 

 been prepared by John A. Allan. First in importance comes 

 coal, then rock salt and petroleum (11,718 barrels in 1920) ; clays, 

 iron, etc., are also described. 



9. The Future of the Comstock Lode. — The well-known Corn- 

 stock lode in Nevada, which produced such vast wealth in silver 

 and gold especially in the decade following 1859, has been 

 studied anew by the U. S. Geological Survey. In a recent leaflet 

 it is remarked that the fundamental geologic problem is the per- 

 sistence of the ores with increase in depth. If the rich silver 

 ores were deposited wholly or largely from solutions that 

 ascended from sources far below the surface, deeper exploration 

 is fully warranted. If they owed their richness to the action of 

 descending surface waters on ores that originally contained rela- 

 tively little gold and silver, then there is little to encourage 

 deeper mining. The .steady progress in metallurgy, by which 

 more metal is recovered from low-grade gold and silver ores, has 

 given large practical importance to the question of the per- 

 sistence in depth of ores of this class. 



E. S. Bastin has made a microscopic study of the Comstock 

 ores. In his report (Bulletin 735-C) entitled "Bonanza ores of 

 the Comstock Lode," he concludes that in the ores from depths 

 greater than 500 feet, which include most of the bonanza ores of 

 the lode, the silver is practically all in primary minerals. 

 Descending solutions of surface origin produced a large increase 

 in the silver content of certain ores obtained within 500 feet or 

 less of the surface, yet even at those depths a part of the silver 

 is contained in primary minerals, and some rich ores taken from 



