I think the more interesting question isn't really what you carry but where you go. If you can control where you go (doesn't really matter when, as long as its >250 years ago) the obvious answer in my opinion is you take enough documentation to recreate the Bessemer process and steam engine, some historical prospecting maps, and as much gold as you can carry to pay for the manpower to build everything. If you pick the right spot (assuming it's populated) near known easily accessible iron, coal, and other mineral deposits, you'd be able to begin the industrial revolution centuries or millenia before it actually happened. The Romans had water wheels, rudimentary steam engines, steel, and coal but all of the easily accessible materials were spread out across several continents so there wasn't enough available to really develop towards industrialization. There's no real reason the technologies couldn't be bootstrapped with the right geography. It really isn't a stretch to add a section on gunpowder to the documentation and leap another age or two, bringing guns to the iron age. If my Empire Earth simulations are anything to go by, it would lead to total world domination in short order (which would then quickly collapse because long distance communication would still be centuries away).
The problem with taking something like aluminum is that until it was plentifully available, no one had any idea what to do with it and it wasn't really worth all that much. I've got a 1867 Scientific American with several articles/letters to the editor arguing back and forth over its future potential with one side emphasizing the fact that since it was so rare, few people had access to it to develop technology to use it and so there was little demand. You'd basically have to bring the rest of modern civilization with you to make the material useful and valuable in a human life time. Same with computers, anything that runs on refined fossil fuels like gasoline or electricity, and so on.
The problem with taking something like aluminum is that until it was plentifully available, no one had any idea what to do with it and it wasn't really worth all that much. I've got a 1867 Scientific American with several articles/letters to the editor arguing back and forth over its future potential with one side emphasizing the fact that since it was so rare, few people had access to it to develop technology to use it and so there was little demand. You'd basically have to bring the rest of modern civilization with you to make the material useful and valuable in a human life time. Same with computers, anything that runs on refined fossil fuels like gasoline or electricity, and so on.