a few mineral suggestions: iron: half the density of steel, so should have half the stats, as well as half the cost plastic: 1/3 the density of aluminum, same crash tolerance, 1/3 the heat tolerance concrete: 3x as dense as steel, 100mps crash tolerance, VERY heat resistant paper: with just 10 plates, it's only 0.1 tons, very low crash speed (5) low heat resistance (400) that's all i could think of with real minerals