> chemical resistance I remember from a freshman chem lab that trying to dissolve aluminum into acid doesn't work because acid promotes oxide growth, so we dis

> chemical resistance I remember from a freshman chem lab that trying to dissolve aluminum into acid doesn't work because acid promotes oxide growth, so we dissolved it in NaOH, which was supposed to attack the oxide, then acidified the solution. Are the aluminum oxide minerals similarly susceptible, or do they also resist alkali?