alluvial which occurs in mammillary (breast-like) nuggets, and is of a
higher degree of purity as gold.

The ordinary non-scientific digger will do well to give credence to
this view of the case, and will often thereby save himself much useless
trouble. Sometimes also the alluvial gold, coarser in size than true
reef-born alluvial, is derived almost _in situ_ from small quartz
"leaders," or veins, which the grinding down of the face of the slates
has exposed; these leaders in time being also broken and worn, set free
the gold they have contained, which does not, as a rule, travel far, but
sometimes becomes water-worn by the rubbing over it of the disintegrated
fragments of rock.

But the heavy, true alluvial gold, in great pure masses, mammillary, or
botryoidal (like a bunch of grapes) in shape, have assuredly been
formed by accretion on some metallic base, from gold salts in solution,
probably chloride, but possibly sulphide.

Nuggets, properly so-called, are never found in quartz lodes; but, as
will be shown later, a true nugget having all the characteristics of
so-called water-worn alluvial may be artificially formed on a small
piece of galena, or pyrites, by simply suspending the base metal by a
thread in a vessel containing a weak solution of chloride of gold in
which a few hard-wood chips are thrown.

Prospecting for alluvial gold at shallow depths is a comparatively easy
process, requiring no great amount of technical knowledge. Usually the
first gold is got at or near the surface and then traced to deep leads,
if such exist.