It's easy to get spectral information about asteroids, from the JPL database for instance. They often have an albedo estimation, but almost never have a mass estimate (if you have albedo and mass, then you roughly have density).
So the natural question is if we can just estimate density generally for the spectral class of an asteroid. Wikipedia has to say on the subject:
However, a better guess can be obtained by taking into account the asteroid's spectral type. A recent paper gives calculations for the mean densities of C, S, and M class asteroids as 1.38, 2.71, and 5.32 g/cm3. (Here "C" included Tholen classes C, D, P, T, B, G, and F, while "S" included Tholen classes S, K, Q, V, R, A, and E). Assuming these values (rather than the present ~2 g/cm3) is a better guess.
The reference is from 2002, and if you follow it, you can get something that does the job like I'm talking about.
Even with their revised estimate, I imagine that this is pretty out of date. Have there been any updated density estimation methods based on spectral information published? Or (even better) is there a code available somewhere online that will do this?
You can relatively easily get up-to-date tables of meteorite densities, but this doesn't translate into what I'm looking for, because you would have to a) connect meteorite type to spectral class, and b) it's definitely proven that this method is wrong anyway because of porosity.