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美国地质调查局对美国大约 99%的原始资源量在 2t以上的金矿、 85t以上的银矿、 5 0 0 0 0t以上的铜矿、3 0 0 0 0t以上的铅矿和 5 0 0 0 0t以上的锌矿进行了统计 .从 1996年的全国矿产资源评价开始 ,美国地调局系统地建立了这些矿床的数据库 ,统称之为“主要”矿床 .截止至 1996年 12月 3 1日 ,该数据库已收录了 1118条单个矿床或矿区的记录 .对于这种规模的数据库的维护、更新和分析要比管理诸如“矿产资源数据系统”和“矿业地区系统”等超过 10 0 0 0 0条记录的数据库容易得多 .然而这个主要矿床数据库却包含了美国这几种金属矿床几乎所有的历史产量和已查明的保有资源量 .约有 3 0 %的金、 2 2 %的银、 42 %的铜、 3 9%的铅和 46%的锌产于二战后发现的矿床中 .即使在一个主要矿床的数据库中 ,也存在个别矿床中的历史产量及保有资源量分布不均匀的现象 .每一种金属的最大 10个矿床分别拥有了美国 1/3的金、 60 %的银、 68%的铜、 85 %的铅和 75 %的锌产量 .从查明的保有资源量上看 ,最大的 10个矿床分别占有 43 %的金、 5 6%的银、 48%的铜、 94%的铅和 72 %的锌 .每一种金属的主要矿床的查明资源量要低于 1996年全国矿产资源评价对未发现矿床资源量估计的平均值 .已查明资源量与累积的历史产量大体
The United States Geological Survey estimated that about 99% of gold mines with over 2t primary resources in the United States, more than 85t of silver ore, more than 5000t of copper ore, more than 3000t of lead ore and 500o 0t above the zinc ore statistics.From the national mineral resources evaluation in 1996, the United States to establish a systematic database of these deposits database, collectively referred to as the “main” deposits as of December 31, 1996, The database contains records of 1,188 individual deposits or mines, and maintenance, updating and analysis of databases of this size is more efficient than managing over 10 0 0 0 items such as the Mineral Resource Data System and the Mining Area System The recorded database is much easier, however, but this major deposit database contains almost all of the historical production of the metal deposits in the United States and the amount of retained resources identified, approximately 30% gold, 22% silver, 42% % Of copper, 39% of lead and 46% of zinc were found in the deposits found after World War II, even in the database of one major deposit, with the historical production in individual deposits and the uneven distribution of retained resources. every kind The largest 10 deposits of metal each have one-third of the U.S. gold, 60% of silver, 68% of copper, 85% of lead and 75% of zinc, respectively. The largest 10 The deposits account for 43% of gold, 56% of silver, 48% of copper, 94% of lead and 72% of zinc, respectively. The identified resources for each of the major metallogenic deposits are lower than the national mineral resources Evaluation of the average value of the undetected resources Estimated resources have been identified with the accumulation of historical output