Coal is still a dominant fuel in America, Australia, China, Mongolia and Russia, but more and more countries are abandoning coal and turning to alternative sources of energy, increasingly renewable energy provided by wind, wave or solar power. So now is an opportune time to take stock of the impact that coal and coal mining have had on countries around the world. Some 48 countries have institutions recording or commemorating that history in the form of museums, heritage centres or preserved colliery sites, of which this book considers 432 examples. It is not a straightforward account of the history of coal mining but rather an examination of how that history has been presented by different institutions and cultures.

In their paper, Marcotte and Boucher (2001) cast some new light on the old problem of 2D estimation of vein-type deposits with thickness and grade of intercepts. Using a theoretical approach, some extensive simulation experiments and the Walker Lake data, they show that the direct approach (interpolation of grade at points on a regular grid) gives better estimates of the true grade at those points than the indirect approach (interpolation of grade x thickness or accumulation and interpolation of thickness) when there is some positive correlation between grade and thickness and that this better performance increases with the correlation of grade and thickness as well as the variability of both variables. We would like to bring some reservations to that conclusion by showing that even if direct point grade estimates are better than indirect ones, it is not necessarily true for block estimates and in particular for the estimated grade of the whole orebody itself. <...>

Conventional oil and gas are usually found in pore spaces and fracture openings of sandstones, limestones, and dolomite. Shales, although considered to be important in many cases as source rocks and cap rocks for hydrocarbons, usually do not contain commercial oil and gas. In other words, from the standpoint of production, shales are relatively useless rocks.

If, for example, an exploratory well were drilled and a geologist tried to evaluate whether it had penetrated oil and/or gas accumulations, he would first separate the shaly sections as being of no interest, and then try to find out whether the other sections were oil-(and/or gas-) saturated or watersaturated. <...>