Aluminum - Very hard to acquire without the Bayer process, Thus, rare post-SHTF, as well as not very dense. My biggest concern is that nobody who survives would realize its value. Iron - middle of the road. Not as valuable, but useful. Titanium - Valuable, light, and good to make stuff with. I don't know, but I'm assuming it'd be hard to work with.
I have thought about it because I understand how much silver we consume. Somewhere on the site, there's a video describing how rare silver will become and the point of the video is to describe the values that silver will see as opposed to gold. However, I see that rarity as a reason to start holding other metals that have similar properties as silver. Reason being, if silver becomes TOO rare, other metals will start being used OR we'll just have lower quality products that don't use silver. For example, do you think Apple will just stop making computers, quadruple their prices because they continue to use silver, or find the next best metal to use? I think the latter. I'd like to find out more about what that metal could be.
If you're talking about speculating on the commodities market, there surely is some opportunity for making money with base metals there. On the other hand, I'm not sure there's much sense in buying and physically holding onto base metals. The quantities you'd need to hold would not be cost effective for the average person. Sure, if you have empty warehouses sitting around that you don't have any other plans with, that might work, but I don't know anyone in that position. I would be interested in knowing what base metals might be able to replace not only silver, but other precious metals that are used in industrial processes.
Honestly, I don't know enough about science to throw any metals out there. I know that silver is the best at a lot of things, which means that other metals may be able to do things... just not as well. So, I am only making the assumption that other metals may play a bigger role someday. There has been a lot of talk about silver no longer being affordable if it continues to be consumed the way it is. Would companies really have a choice besides using another metal to do certain things? I couldn't imagine paying $5000 for a computer just because it's full of silver, you know? And if it becomes scarce, wouldn't the medical field need it more than any other field? I would HOPE, as a human race, we'd allow the majority of silver to head in that direction. That's wishful thinking, though.
Investing in Aluminium, Iron and Titanium? Are you kidding me? I have never thought about investing in them. Even if we buy Titanium and Aluminium bars, how we would be able to sell them? Also storing them will be another problem. Other than gold and silver, I think Platinum and Palladium are good for investing. Rhodium sponge is also getting more interesting now.
honestly i never though of investing in anything else other then gold and silver, but now as i see this thread, i may think ofplatinum, also brain storming to invest in iron and steel, aluminium, copper in physical form.