Gold in the Sardis Placer Deposit: Composition and Source of King Croesus's Gold

Abstract

In history, Sardis was important for its wealth derived from placer gold in the Pactolus River which erodes an alluvial fan containing the gold, thought to be derived from erosion of the Menderes Massif. We have shown that the exterior of gold grains was modified in the placer by biological and chemical processes. LA-ICPMS analyses indicate the presence of significant numbers of PGE particles and mineral inclusions that cast doubt on the source of the material in the alluvial fan. We propose that the gold in this alluvial fan was derived from laterization of the ophiolites that now form the Caldag laterite deposit prior to tectonic movement of the ophiolite unit to the NW. This is a Ni deposit and contains gold in some of the laterite units. The mineralogy in the alluvial fan at Sardis is also similar to some laterite units at Caldag.