Mercury has a lot of similarities to Earth and to Earth’s moon. First, this planet has a core, mantle and crust just like Earth. However, Mercury’s core is much larger compared to the ratio of Earth’s core to the rest of its composition. Mercury has many craters and rocks on its surface. Iron makes up some if not most of the core of Mercury. Comparatively speaking, Mercury’s crust is much thinner than Earth’s crust.
Since Mercury is not explored directly by astronauts due to it being so close to the sun, there is no way to be definite. However, it is expected that Mercury’s crust is made of basalt. This basalt contains a lot of magnesium in it. Probes have been set on Mercury to help with the exploration.