In shallow water on a few of our beaches alone we have pure iron sands at over 40% iron concentrations alone. In river mouths recently tested that number approaches higher than 65% iron content, with 80% of the material being iron-sands. The only problem with these deposits is the pressence of a form of titanium which must be either separated beforehand so as not to jam the smelter, or it must be smelted at fairly high temperatures. Such a thing never happened in real life only because of a lack of funding and expertise made available to the industrial sector of a small farming colony at the time of WW2. It would have been entirely possible to have achieved production within half a year had it become an imperial issue and been considered vital to the war effort, subsequently recieving full imperial support in the development of it's exploitation. In comparison this not only dwarfs the slag deposits from hundreds of years of smelting at an old italian village (from which over half the navy and airforce of italy in ww2 was made of) by quantity/ready_availability, but allso by cost of extraction. As since it is all on sea no roading infrastructure is required, little-no factories need to be built and dismantalled/written off, transport is not expensive. This is because you can have factory ships, dredgers, transports and logistics all supplied by ships, many from retrofitted merchant/naval ships.
Furthermore we produced oil during the war, we had radar installation that intercepted messages 1000s of KMS away, we had the largest archery club in the empire, most of our people had knowledge in at least one field of science in addition to their specialty, we where able to field several brigades and a destroyer group and airforce. In addition to that our main port was very heavily deffended by several large fortified anti-naval guns with underground bunkers. These where supported by a network of tunnles extending within and between the islands. All the military basses where built in underground bunkers to protect personel and equipment from bombing. Even our anti-air flack guns would be stored underground and pushed back up when we have contact. There where pillboxes everywhere, so many infact that I the closest beach to where I live is called "blockhouse bay". We had many underground storage deopts. The ports where defended by anti-submarine nets and searchlights. Yet my country is litterally the second worse minor power in the game, no resources, no manpower, no radar (even though it was pivotal to war efforts and was a major installation during the war and is still in used today), no leadership (which is a lie, my great grand father alone built the worlds largest telescope in the southern hemishpere, founded our astronomical society, conducted selective breeding experimentation and cross breading on crops, worked as state engineer, did hiking, was in archer club, volountered at community services, etc..etc..etc.. and he only one man..). It is absolutely ridiculous that you can not order such a readily available source of iron to be exploited when you are part of the most powerful empire in the world and are extracting it from much harder places elsewhere. Point is for being so resource rich we don't even have any of our resources show up in game (at all), nor do we have our leadership and infrastructure that was pivotal to american war effort in pacific ocean etc..etc.. This is a nerf against the british empire, and as usa war production increased so too did there metals production in real life.
For smaller countries not allready at or anywhere near peak production potential of resources, for nations with lots of resources untapped increasing resource production is important to expand. Yet you can not do this, and in game USA is modelled as if it was at peak production whilst germany never expanded. Furthermore when you invade a place apparently a mine will produce less because we are now running it -.-... All this hampers Germany which would if not for losing aerial superriority had, hah a much larger minning rate. If they had seized property and mines, and had they implemented forced labour they could have increased production furthermore. Without the resource rediversion from aerial bombardments, the growth in resource extraction and the full devotion towards arms expansion would of outstretched that which you can achieve in game with occcupying france... I conclude that the lack of ability to expand primary sector economy and the nerf on occupation is as a game ballance and an attempt to stray away from codding a more complex aspect to gameplay. Oh and in real life germany did increase production of coal and rares, infact the largest company in the world was the german rares company.