If mineral veins sometimes resemble botanical illustrations, blame it on Earth's molten nature and fluid mechanics: when seen from above, a branching river also looks like a tree.

Abandoned veins in mineral-rich countries have become viable again-and despite the relatively steep extraction costs, a miniature gold rush might be under way in Britain, too.

The types of veins increase, the mineral components get more complicated and higher temperature hydrothermal minerals evolve as the anthracite metamorphic ranks, whenever they are, get higher.