Page 41 - Handbook of Gold Exploration and Evaluation

22 Handbook of gold exploration and evaluation

factors. Figure 1.5(a) depicts a gold grain as a composite of four different gold
particles x, y, v and z, held together by `new' high-grade gold, the black zone
represents a vugh in the central part of the grain. Figure 1.5(b) is a composite of
two gold particles of different composition held together by new spongy gold of
lower Ag content. The new spongy gold (z) has the lowest Ag content (average
weight percent). Figure 1.6(a) sketches a polished section of a strongly bent gold
grain, which has two different, consecutive generations of rims. Figure 1.6(b) is
a sequential representation of the evolution of a gold particle in a placer
assuming an originally larger unbent grain. This model is a simplified model,
which assumes an original unbent grain. Giusti (1986) suggests that if the gold

1.5 Sketches of polished sections of two composite gold grains (from Giusti,
1986).