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Occasionally there are news about a major ore deposit for a specific commodity being found. Some of these recent discoveries are underground, and the "geophysics" aspect of their exploration is more important than the "geology" aspect.

This makes me wonder—are there any such known ore deposits that have been found under cities? Some examples might be "the largest gold deposit ever, under Buckingham Palace" or "diamond bearing kimberlite pipe under Central Park in New York".

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    $\begingroup$ Not Buckingham Palace, but an oil exploration well was drilled under Windsor Castle in the 1990s using horizontal drilling! $\endgroup$ – winwaed Dec 23 '14 at 14:41
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    $\begingroup$ Los Angeles was built on top of an oil field: en.wikipedia.org/wiki/Los_Angeles_City_Oil_Field $\endgroup$ – DA. Dec 23 '14 at 14:53
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    $\begingroup$ Unless existing deposits near a city lead to suspicion if under the city there is something, I would not expect much prospection going on inside or near existing bigger cities, so even if there is a kimberlite pipe under central park, it is likely that it will not be discovered before most other places are depleted. $\endgroup$ – PlasmaHH Dec 23 '14 at 15:09
  • $\begingroup$ @PlasmaHH actually I had this thought 5 seconds after hitting the submit button :) $\endgroup$ – Gimelist Dec 23 '14 at 15:13
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One example of an ore deposit that runs under a city is the banded iron formation ore in Kiruna. In this case the ore has been mined outside of the city since the turn of the previous century. The ore has been found to run under the city and there are now plans to move the city more detailed information. This has led to a process where the city has to be re-established in a different location including moving a large number of historically significant buildings.

A similar situation is also present in Malmberget (about 120 km S of Kiruna), part of the twin town of Gällivare-Malmberget. In this case the plan is to have Malmberget inhabitants to move to Gällivare. The mining activities at Malmberget have resulted in several collapse features see images on this link. There is also some information in English on the Gällivare web-site.

In both cases there are significant restructuring of the societies. It is also worth noting that the definition of ore is economical which means that what is worth mining depends on market prices. In the case of Iron the market has been strong but has fluctuated significantly. The result is that the planning and decisions for a move such as these are difficult since they are costly and depend on the market to be financially viable (it is the mining company that largely pays for the move).

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    $\begingroup$ I was thinking "there is that town in Sweden" - didn't realise it was a BIF :-) That will be good ore! $\endgroup$ – winwaed Dec 23 '14 at 14:42
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    $\begingroup$ Reminds me of the mercury mind in Idrija, Slovenia. The mine grew from its humble beginnings, and now underlies the city. $\endgroup$ – Gimelist Dec 23 '14 at 15:23
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Quite a few cities were built overtop of ore deposits. They often started out as a series of small workings and larger, deeper deposits were found as the cities grew up to support the mining.

An example is Bendigo Australia where there were mines under the centre of town

Mining has continued off and on with the most recent activity using a decline for trucks to reach the the ore at a depth of ~ 1km

enter image description here

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