Zircon, native gold and amalgam rim. Gold concentrate. Brazil




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125µm


Rounded to subhedral zircons (dark greys) show faint internal reflections about their margins. Native gold (yellow, centre) is enclosed within an amalgam rim (pale yellow-white, centre) which is still partially covered by carbon-coating (reddish areas). This amalgam rim could be confused with supergene gold rims but amalgam is whiter than the gold core rather than yellower (see Plate 45) as is the case for gold enrichment rims. Blue-grey areas around zircon and gold grains are relict carbon-coating.


Grain mount, plane polarized light, x 160, oil



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