I do have a cube of solid aluminum. But I need to verify that it is really Al to validate my research. What simple scientific techniques do you recommend?
If you want a simple one, then you might want to just perform qualitative analysis (QA) using aqueous sodium hydroxide and aqueous ammonia. Firstly, dissolve a portion of the cube using a small volume hydrochloric acid. Then, add a small volume of sodium hydroxide to a small volume the metal chloride solution. To another small volume of the metal chloride solution, add a small volume of aqueous ammonia.
For the first test, aluminium ions would first give a white precipitate but will dissolve in excess. For the second test, aluminium ions would first give a white precipitate but will not dissolve in excess.
Lastly to confirm, add aqueous potassium iodide to the sample. If no precipitation occurs, the sample is indeed aluminium chloride solution and the cube does indeed contain aluminium.
Alternatively, this paper here also provides some insights on verifying if something is indeed aluminium:
Unfortunately, the method I have mentioned and the methods in the paper are destructive as they require you to chip of a piece of metal from the cube for analysis. So... if you can't afford to do that then they cannot be used.