Gold exploration techniques are not perfect and have limitations. In the case of geochemical techniques, one of the major unresolved problems is related to the interpretation of geochemical surveys over vein type is to distinguish between anomalies associated to economic gold mineralization and anomalies associated to non-economic gold mineralization in veins and minor mineralization in faults. In some circumstances, a distinction between two zones lies in the contrast to threshold. For example, 0.5 to 30 g/t and 0.01 to 1.0 g/t. There are some gold veins with high mineralization.
There is a suggestion that some classification of vein type anomalies may be possible based upon anomaly-contrast and width. For example, anomalies with a contrast to threshold ratio of less than ten over a distance of less than 60 m might be disregarded for further work. Obviously, considerably more data is needed to estimate even the statistical probability of such mathematically expressed relationship being valid for exploration work. Exceptions to any such generalization will almost certainly be found by geologist and experienced golf prospectors.
Basically, the broad differences in interpretation of data from disseminated gold deposits occurrences compared with vein type mineralization are obvious. Equally important in the successful application of soil sampling to exploration is the difference in sampling patterns. In the case of disseminated gold deposits, the odd sample point, more or less, and their precise disposition on a sample interval such as 20 m, make little difference to the overall pattern. On the other hand, individual sample points are critical, as is the positioning of the traverses. Gold mineralization associated with major faults or their intersection with other faults and with the occurrence of some rock beds provides a favorable horizon and lithological control. It has been noted that after a preliminary reconnaissance, additional sampling and analysis for gold form the basis for detailed geological investigation in a covered area to substantiate and modify the correlation of geochemical anomalies. In some circumstances, extremely rugged nature of the terrain precludes sampling in any irregular pattern, and it is not possible to take a sample in the correct point or location. When the deposit is not complex, the distribution of gold in the soils that can be sampled, faithfully reflects its distribution in bedrock.