Also you need to think about what would happen if you were to work overseas. Mining can be a very international job. The country I work in has a lot of mining going on in it at the moment with workers from Canada, USA, Australia etc all being involved. To work in an overseas country you will need a work visa and one of the questions you will have to answer is whether you have a criminal conviction and be able to prove it with a police clearance from your home country. Of course just because you have one does not mean you will be denied a visa (there are at least two people who work in my company doing my job that have criminal records).
On the other hand whatever you decide to persue in life surely you would be better off with further education than without it? If you don't further your education you will still have a criminal record and no degree/diploma which I would have thought would be a weaker position than with the said degree/diploma.