When a gold prospector is looking for a gold placer he must sample some key points during his prospecting activity. In this way, streams crossing the lamina or stratification planes of gold reefs at right angles are usually the richest points. Also, gold is rarely detected where there are indications that the current was strong, but rather in the lee under projecting points of rock where beaches are usually formed and the water was flowing slowly. Gold in streams is deposited in crevices of the bed rock which should be laid as dry as possible and picked up to such depths as the sand descends between laminations. Terraces are shelf like excavations and deposits upon hill slopes above valleys and the remains of old glacier or river beds. The prospector should discover the inlet and outlet of the terrace and examine the gravel. The wash sometimes contains gold in layers one above the other.
It is important to mention that when prospecting up stream, the prospector must be focused in the banks on each side where sections are exposed so that no outcropping vein will be overlooked. Alluvial gold could be found when the gold is large and plentiful and the boulders large and angular and the reef is not far. In some occasions, there is a distinct peculiar feature in all the veins of a district such as peculiar band of a definite color. Coarse alluvial gold is not always incompatible with fine reef gold as a source due to reef gold may be so fine in general as to lend itself to very wide distribution when once is liberated, while the rarer coarse grains would not be transported far.
Alluvial placers are important source of gold and the key points for prospecting are where the current of the stream is interrupted by diminution in fall, sudden change in direction, entrance of a tributary, reefs or eddies. Basically, absolute richness depends upon local characteristics. Creases, holes and fissures of bed rock over which the stream passed are favorite places. The lowest layers of each separate period of deposition have succeeded each other. The course of present streams and of old channels are potential places where the prospector must explore and take samples.
Reef prospecting involves locating gold bearing quartz veins. Most of the accessible reefs have probably been found by early prospectors and explorations; consequently, remote and poorly outcropping reefs are more likely to be found. Actually, in the short term, this form of prospecting is not as rewarding as metal detecting. Surface weathering of outcropping quartz reefs distributes gold away and down slope from the reef, resulting in the formation of alluvial and eluvial deposits. Consequently, it is possible to trace the alluvial or eluvial deposit upstream and upslope until the source reef is located. Often, the reef has been completely weathered away, leaving only alluvial and eluvial deposits.