Yeah, it does seem a little weird, but the color itself is basically right. For reference, this is what a rock made entirely of olivine (dunite) looks like (my own find).
A big portion of the mantles of silicate planets is made of this stuff, and it can be brought to the surface by tectonic processes, so it can cover large areas of the surface. This rock came from an entire mountain made of it. In the presence of oxygen it gets an orange coating to it though, so the mountain itself is orange instead of green. But on a desert planet with no oxygen in the air? Maybe it's not that unrealistic.