From some quick Googling (no, I don't know the hardness of bone off the top of my head though having worked with it I can say it's quite soft just like aluminum

From some quick Googling (no, I don't know the hardness of bone off the top of my head though having worked with it I can say it's quite soft just like aluminum), it looks like aluminum and bone aren't that different in hardness or toughness, with aluminum alloy being somewhat harder and tougher at the expense of higher density.