Most of our atmospheric oxygen comes from photosynthesis, and most of our regolith is either sand or filled with biomass. So my guess is that you're looking at mostly sand, with the precise details depending on things like chemical abundances, the density, temperature, etc of your planet, and the presence or absence of water (the absence of water on the surfaces of Mars and the Moon seem to be part of why their regoliths are so much finer than Earth's sand).
It's hard to get specific without more information. Ex, is the planet lifeless because it's too hot / cold / dry / full of toxic chemicals / has too thin or thick an atmosphere? How big is it, both in terms of mass, and radius? Orbits and rotations will also affect the temperature. Is it geologically active? If so, you'd expect more basaltic and basalt-derived rocks and regolith.
I find this page useful. It's on the long side, but has clear subsections for surfaces, regolith, atmosphere, etc. It does, though, leave a great deal open-ended, since the precise surface composition can vary based on a variety of factors.
The planet you described sounds to me like it's somewhere between Earth and Mars. Given that, I'm guessing an Earth-like sky, with landmasses mostly covered in sand, with flood basalts and basaltic sediments optional depending on how geologically active this planet has been. However, you could easily go with something more Lunar (more vulcanism and less water) or Martian (lots of surface iron oxides). You could probably get away with copper compounds if you want blue sand, but you'd need to explain where the iron and silicon went (maybe blue sand wouldn't realistically cover more than a small area?).