苗龙矿区赋矿地层为寒武系上统三都组灰岩和泥灰岩,矿体严格受断裂构造控制,矿体主要赋存于东西向Fm1、Fm14断裂中。矿床成矿作用可划分为3个期次,即沉积成岩期、热液成矿期和表生氧化期。毒砂为热液成矿期主阶段重要产物之一,主要呈菱形体、针状、柱状及放射柱状集合体产出。通过对毒砂进行电子探针分析及面扫描分析,结果表明毒砂中主成分稳定,w(Fe)为32.47%-35.71%,平均34.05%;w(S)为21.01%-26.38%,平均为23.13%;w(As)为38.50%-44.73%,平均为41.86%。其成分(FeAs0.80S1.17-FeAs1.02S1.21)明显偏离理论毒砂的成分(FeAs1.12S1-x≤0.13),具有富硫亏砷等低温热液特征。毒砂含金性较好,w(Au)为0.05%-0.14%,平均为0.06%。面扫描图像中,Au元素分布均匀,说明Au主要以晶格金(固溶体金)形式存在于毒砂中。
The ore bodies of the Miaolong gold deposit are hosted in limestone intercalated with marlstone of Upper Cambrian Sandu Formation.The gold ore bodies are strictly controlled by Fault Fm1and Fault Fm14.The oreforming process of this deposit can be divided into 3 stages,i.e.,diagenetic stage,hydrothermal mineralization stage and supergene oxidation stage.Arsenopyrite is one of the essential products of the hydrothermal mineralization stage and occurs as rhombic,acicular,columnar and radiate-columnar aggregates.The components of arenopyrite(FeAs0.80S1.17-FeAs1.02S1.21)are deviated obviously from the theoretical arsenopyrite components(FeAs1.12S1-x≤ 0.13)and show epithermal characteristics of enrichment of S and depletion of As. The asenopyrite is rich in gold,and the content of gold is 0.05%-0.14%,with an average of 0.06%.Au is uniformly distributed in the SEM diagram,suggesting that Au exists in the arsenopyrite in the form of lattice gold(solid solution gold).