| 陕西小秦岭金矿床中金的赋存状态及分布规律 |
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| 引用本文：.1996.Modes of occurrence and distribution of gold in Xiaoqinling gold deposits, Shaanxi Province[J].Mineral Deposits,15(1):71~79 |
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| 基金项目:地矿部黄金专项项目 |
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| 中文摘要:陕西小秦岭脉状金矿床中，金的赋存状态及其分布与硫化物的发育程度密切相关。金优先赋存于硫化矿物中，只有当硫化物不发育时，才主要以金矿物形式赋存于石英等矿物中。金矿物的Ag/Au比率主要受成矿温度、硫化物发育程度、成矿热液中Cl/S浓度比值等因素制约。 |
| 中文关键词:脉状金矿床 硫化矿物 金的赋存状态 金矿物成色 陕西小秦岭 |
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| Modes of occurrence and distribution of gold in Xiaoqinling gold deposits, Shaanxi Province |
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| Abstract:In the Xiaoqinling vein gold deposits of Shaanxi Province, modes of occurrence and distribution of gold are closely related to the development of sulfides. Gold (including gold minerals and ultramicroscopic gold) preferentially occurs in sulfide minerals, especially in pyrite and sphalerite; nevertheless, where sulfides are poorly developed, gold mainly occurs in non-sulfide minerals such as quartz. Orebodies of vein gold deposits are mainly sulfide quartz veins, and where there exists intense wall-rock alteration, the near-ore altered rocks constitute the component part of an ore body. Gold minerals mainly include native gold and electrum, which occur in three forms: "intergranular gold" that exists among grains, "fissure gold " existent in microfissures of minerals; "enclave gold" wrapped in minerals. Of these three forms, the last two belong to gold minerals that occur in other minerals. In gold deposits, the better developed the sulfides, the more the intergranular gold, and the less the fissure gold. According to development characteristics of sulfides, the vein gold deposits might be divided into three types: polymetallic sulfide type, pyrite sulfide type and sulfide-deficient type. In polymetallic sulfide type gold deposits, gold minerals mostly occur in sulfide minerals, and their average finenesses are lower than 800; in pyrite sulfide type gold deposits, about half of gold minerals occur in sulfides, and their average finenesses are between 800 and 950; in sulfide-deficient type gold deposits, gold minerals mostly occur in quartz,and their average finenesses are higher than 950. The finenesses of gold minerals gradually decrease with the fall in ore-forming temperature and also with the drop in the ratio between concentration of chlorine and that of sulfur. Besides gold minerals, there is a large amount of ultramicroscopic gold (invisible gold) that occurs in various minerals within ore deposits. The variations in ultramicroscopic Au and Ag in various minerals show regularity instead of being at random. In the same ore deposit, ultramicroscopic Au content of various minerals varies in order of pyrite＞sphalerite＞galena and chalcopyrite＞quartz, whereas ultrarnicroscopic Ag vontent varies in order of galena＞sphalerite, chalcopyrite and pyrite＞quartz, suggesting that Au and Ag tend to be concentrated in pyrite and galena respectively. It is preliminarily considered that ultramicroscopic Au takes part in the formation of lattice structure of minerals instead of being present in lattice defects of minerals. |
| keywords:vein gold deposit, sulfide mineral, mode of occurrence of gold, fineness of gold mineral, Xiaoqinling of Shaanxi |
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