The more i study this strange element, the more interesting it becomes. I found that bismuth only shows it's colorful oxides when exposed to air while hot/molten. I decided to go outside and polish the sample using an abrasive liquid known in Brazil as "Saponáceo Cremoso". Don't know what it's called in english-speaking countries. Edit: It's called "Scouring cream" in english. Anyway, it's used to polish aluminum cookware as well as any other metal surfaces. So i took my bismuth sample out and started polishing. The metal finally showed it's natural appearance: A lustrous, shiny and silvery material that resembles lead or iron. But something more happened: It didn't oxidize. Even after being exposed to air, water or even the oils from my hand, it's still shiny, without any noticeable color change. But when molten, it tarnishes instantaneously! Anyone knows why?