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印度南部怀纳德金矿区尼兰布尔河谷中的砂金颗粒以纯度非常高(985～1000)为其特征。砂金的核心成分贫银、颗粒大和微型生长形式都可以与风化基面中的红土剖面有关的金粒对比。根据与本区原生矿床、表生矿床和次生矿床有关的金粒的形态和化学演化,鉴别了高纯度砂金矿的两阶段演化过程,它表明原生矿脉中的金活化转移、化学纯化并重新富集在红土剖面中,对金被迁移到水系中去之前纯度的增高和颗粒的生长都有影响。在河水搬运过程中金得到进一步的纯化,产生了砂矿中高纯度砂金的富集。 分散的金粒离开其原生源区的机械位移、在水系中的机械搬运以砂矿的形式富集起来是产生金的经济富集的潜在方式之一。金粒的河水搬运常常能够使银淋失掉而提高其纯度。然而,在表生环境中,在其迁移到水系中去之前,金的化学纯化变纯的机理可以在砂矿中产生纯度非常高的金的富集。 本文报道印度南部怀纳德金矿区尼兰布尔河谷中的这样一个例子。研究表明,在单个颗粒范围内,形态的演变和化学成分的变纯能够为确定金的来源的特点提供有益的线索。
Sedimentary gold particles in the Nilanbur Valley in the southern Indiana’s Nahuad Goldfield are characterized by very high purity (985-1000). The core component of placer gold is lean silver, and the large grain size and micro-growth pattern can be compared with the gold grains related to the laterite profile in the weathered basal plane. Based on the morphologies and chemical evolution of the gold grains associated with the primary, secondary and secondary deposits in this area, the two-stage evolution of the high-purity gold-bearing gold deposits is identified, indicating that the gold in the primary vein is activated and chemically converted Re-enrichment in laterite profiles has an effect on the increase in purity and particle growth before gold is migrated into the water system. Gold is further purified during river handling, resulting in the enrichment of high-purity placer gold in the sand. The mechanical displacement of scattered gold particles from their native source zone and the mechanical handling of the water system in the form of placer ore are one of the potential ways to generate economic enrichment of gold. The river’s handling of gold grains often leads to the loss of silver creams, increasing its purity. However, in epigenetic environments, the mechanism by which chemical purifications of gold become pure before they migrate into the water system can produce a very pure gold enrichment in the sand ores. This article reports an example of this in the Nilanpur Valley in the southern Nahuad Goldfield of India. Studies have shown that the evolution of morphology and the chemical composition of pure particles within a single particle range can provide useful clues for determining the source of gold.