 We talk a lot about renewable versus non-renewable and in theory at least solar for instance is renewable. Now let's ignore the fact that the solar panels are going to wear out and we're going to have to replace them someday and we need minerals to make the panels etc. but let's not go down that. Let's just consider okay those are renewable and wind power and tidal power and other things we can think of are renewable. The non-renewable is things that are held in ancient rocks that might have taken millions of years and very, very specific processes to make. For instance coal is something that we have to go through a very hot period in Earth's history where there's lots of CO2 around lots of plants and then go into a cooling period where a lot of those plants die and get buried. Burry it to the point where it can recrystallize and lifify into coal. This is tens or hundreds of millions a year job so that we have these times in the past where we've made coal beds. We can see them in the Sydney Basin in Australia where there's plenty of coal in there because we were going through a very rare time in our history. We were coming out of a glacial event right then. We had been through a hot event and so the idea is that we have to have very specific circumstances in which we will have the plant life which we're going to bury and we're going to recrystallize into coal. Then we're going to dig that up and that's a one-shot deal. Even if we sought out to make coal now, we're going to be millions of years before we actually have it to use it. That's just one example of many. There are many things that formed mineral deposits in the past. For instance, most of the big gold deposits on Earth are really old. They're during the Archeanum. They took large amounts of fluid to come through the crust and precipitate gold. These sorts of things take a long time and they only have certain epochs in history when these things occurred. So much of Australia's financial security comes from the fact that we have some very large ore deposits. So the Pilbara iron ore is a very special process that happened about two billion years ago and processes had to upgrade it over time and then it had to be exposed at the right level so that it's a very special thing and there won't be another one. That's the same case with Mount Isa lead zinc or the lead zinc in Broken Hill or the Bendigo Ballarat gold fields or all of the Yilgarn gold deposits. All of these are extremely old and happen at very specific times in Earth's history and they ain't going to happen again. So they're non-renewable because yeah of course we can go find new ones. There are some hidden places around the Earth in Mongolia or God knows where in the jungles of Papua New Guinea where we might go find some big deposits but they ain't forming now. They formed sometime in the past.