Iron undergoes a chemical reaction called oxidation to form rust, or iron oxide. ... Copper forms a turquoise colored oxide and silver forms a black oxide. In both cases you know that a chemical reaction has taken place because of the color change.
Uno y dos es pequeno 3 y 4 3s primo
It could be a lump of coal.
Since you can break pieces off, maybe charcoal ... the real thing, not a "briquet".
Do your hands get all black when you handle it ?
