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Jan 1, 1910

Jan 1, 1969

Jan 1, 1907

Jan 1, 1908

[VOL. XXXVI. Page. Line. 155 29 For "Joachimstahl," read "Joachimsthal." 215 Foot-note 2. For " May, 1892," read " May, 1902." 216 21 For " ack-screw," read " jack-screw." VOL. XXXVII. 31 3 For "quantity of tons," read "quantity of slimes." 35 10 Expunge "recorded in Table VII." 37 24 Expunge "to." 38 33 For "page 89," read "page 9." 44 40 For "page 86," read "page 6." 47 In table, third line under heading "Excavators and Conveyors," expunge "per 40 ft. of."]

Jan 1, 1918

Jan 1, 1949

Jan 1, 1953

By A. J. Partos

Table 4, Page 311 Table 4 Experimental Parameters from Straight Line Interpretation of Mohr Failure Envelope [ ]

Jan 1, 1991

Jan 1, 1902

The following figures (Nos. 1-4) and tables (Nos. 1 and 2) were inadvertently omitted from the chapter entitled "Optimum Open-Pit Mine Production Scheduling" by Thys B. Johnson, Section 4, pages 539-562. [ ]

Jan 1, 1969

Jan 1, 1946

Most statistical and geostatistical methods of re-source and reserve estimation work extremely well for Normal (Gaussian) well-behaved information. However, most interesting mineral deposits exhibit far from this idealistic distribution of values. It seems that the more valuable the mineral, the less likely the data are to have a Normal distribution. Values tend to be "positively skewed" with a long tail into the high values. Using averaging techniques, such as inverse distance or ordinary kriging may result in consider-able overestimation of grades and tonnages unless such values are cut or otherwise modified. This paper presents some real case studies where distributions are (a) highly skewed and (b) the product of multiple phases of mineralisation. Practical methods are presented for solving such problems including combinations of indicator and log normal kriging methods. The emphasis of the presentation is on developing operational methods which can be used on project evaluation or grade control in producing mines.

Jan 1, 2000

Jan 1, 1955

The curve of Fig. 3 for pyrite requires modification. There 11% a range of pH values from 6.2 to 7.8 for which no cyanide is required to prevent contact. From 7.8 to 11.3 a small amount of cyanide is required, with a sharp maximum of 20 mg. per liter at pH=9.6. The mistake arose from considering too few solution compositions (17 were considered) in constructing the curve. Subsequent work with other collectors indicates that the corrected curve is typical for such systems; it illustrates the further development of the dip in the pyrite curve of Fig. 5.

Jan 1, 1938

By EDWARD B. DURHAH

The illustration Fig. 12, of the paper of Edward B. Durham, "Electrolytic Refining at the U. S. Mint, San Francisco, Cal.," printed in Bulletin No. 58, October, 1911, p. 830, contained an error. The corrected diagram is printed below.

Nov 1, 1911