Cool Geology of the Day:
This is a meteorite called a pallasite. The silver part is iron-nickel, and the green crystals are a mineral called olivine. Pallasites could represent the core-mantle boundary in large asteroids that were subsequently destroyed. The core, like the core of the Earth, is made up of iron and nickel. Metal and rock (like olivine) can’t mix, much like oil and water, so they separate into a core and mantle.