Good morning!
I did some of this in my original MMO mod, and will be doing the same again when I get to the materials specs. I'll definitely look over your data and see how it compares to mine. If it's OK I'll steal anything that looks better than what I had (with full credit of course!) and include it in the next-gen MMO (in progress).
Rochndil, who got a lot of density info from his handy pocketref...
Enjoy the data
I think I linked up most of my sources either to the research thread, or in some cases, as comments in the raws themselves. A lot of the gems are the same based on broad classifications (quartz gem, corundum, beryl, etc.). I guess you could do more research to try and pin them down. And you might want to check the gem colors for consistency. Sometimes, there is no good color.
You'll also find that I corrected several densities in the raw (e.g. differentiating lignite from bituminous coal), or bumping up ilmenite considerably (it wasn't being given credit). Wolfram Alpha is a good source, but you have to be careful of it's "input interpretation" ... sometimes it tries to pawn off a similar mineral on you.
Finally, you'll find HUGE ranges for some materials (e.g. pitchblende), not to mention that soils are highly variable. I found one interesting source and used it to extrapolate the rest of the soil types, just to get some variation. I'm sure that soils can range a LOT. Interestingly, though it will probably never matter, it seems like the undersea soils are considerably more dense than normal ones, almost to the level of normal rocks. And some things like peat vary greatly depending on water content.
Anyhow, feel free to use and improve the data. And if you can, try to put out an updated version with any corrections or fixes you have. I'm trying to keep this in a form where Toady can use it in DF, so I want to keep the data at least separate from any big mods.
Finally, as for credit, all I did was add non-creative, factual data. Even the formatting is for purely technical reasons. In short, I have no copyright interest in it whatsoever as far as I'm concerned. Toady might, but I don't. So crediting me is appreciated, but unnecessary