That's why I put him as a Virgo.
Remember Piotr is a farm boy at heart. He's all about working the land with his family. He literally turns into metal(a type of earth), and Virgo is ruled by Mercury(silver metal). Virgo is mutable, just as he is, shifting from one form to another. He's friendly, helpful, and hardworking, but can also be self-destructive, uptight, and critical(such as when he rebels against the X-Men after Illyana died, or when Storm was keeping the protomutants from Cyke). He is usually gentle, though, another Virgo quality, and creative(his artistic talents), where his perfectionism also shows through(always critical and doubting of his art, even when it was very good).