Science, Maths & Technology
An introduction to geology
...economically worthwhile. The need to remove very large amounts of very hard igneous rocks means that porphyry ore deposits weren’t mined at all until 1905, when powered shovels and rail transport for the unprocessed ore made them viable. Figure 2.13 shows the Bingham Canyon open pit mine in Utah – you certainly wouldn’t have wanted to dig such a big hole with only...