986 



Subsurface Geologic Methods 



Figure 525. Sterogram showing ore bodies at Childs-Aldwinkle 

 mine, Copper Creek, Arizona. 



datum plane is preferable (fig. 526). In addition, structure, stratigraphy, 

 ore values, and ore widths can be superimposed on the vein-contour map 

 and possible controls observed. 



One important phase in mine examination is sampling, results of 

 which may be a mass of sample numbers, widths, and assay values. De- 

 scriptions and results are usually recorded in a permanent assay book, but 

 they are also shown on the mine maps.^^ Assay values can be recorded on 

 geologic maps, but, if the geology is complex or the samples are too nu- 

 merous, it is necessary to prepare a separate sheet showing only mine work- 

 ings and assay results. For clarity and ease of correlation, assay results 

 may be represented by color. The values also may be plotted near the 

 drift, raise, or stope with one coordinate approximately parallel to the 

 vein and the value coordinate at right angle to the vein trend. To account 



«'McKinstry, H. E., op. cit., pp. 172-173, 1948. 



