地下开采的脉状矿床曾一度占有主导地位.其重要性的相对下降是由于大型采矿设备的发展所致.这些设备使大型露天开采经济合算,并使金属价格在过去十年内长期平平不涨.因而,大公司一般感到小矿床的开采与所耗费的时间和付诸的努力及管理费用得不偿失.他们喜欢大工程,和大规模、低品位的矿床,因为这样易于评估.更复杂的问题是资金的可筹措性.矿业已变得日益依赖于信贷.但银行家们却除非你能向他们提出足以抵偿风险的探明储量, The underground mining of vein-shaped deposits once dominated the relative decline in importance due to the development of large-scale mining equipment that made large-scale open-pit mining economically viable and the price of metals unchanged for the long term in the past decade. As a result, large companies generally feel that it takes less time and effort to manage and manage small-scale deposits, and they like big projects and large-scale, low-grade deposits because they are easy to assess. The more complicated issue is funding Mining has become increasingly dependent on credit, but bankers do not unless you can ask them a proven reserve that is sufficient to cover the risk,