This will only be an estimate, but glass has a density of around 2000-2500 kg/m^3. Sand and glass are pretty much the same thing. Sand will be particles, are assuming that they are all spheres (which they aren't) they can fill around 65% of the space when they are optimally packed. So 0.65*2000 = 1300 kg/m^3 or 1300 g/cc. That should be in the ball park, though not exact. Certainly there are different kinds of sand and the grain will pack differently that spheres, but I think that that estimate will be reasonably close.