Hi All,
Here is a table of weight factors for Trianz, it is quite old and I do not know where it came form now but I find it is fairly close to actual weight density of the varius commodities.
Clay & Gravel	0.85
Coal, Anthracite	0.74
Coal Bituminous	0.74
Rock & Earth 50/50	0.75
Earth Excavated	0.79
Granite Broken	0.61
Gypsum	0.59
Iron Ore	0.85
Sand	0.89
Sand & Clay	0.79
Sand & Gravel	0.89
Sandstone	0.60
Shale	0.75
Slag Broken	0.60
Stone Crushed	0.60
Taconite	0.58
Top Soil	0.70
Rock Broken	0.67
water	1.00
Cheers,
Bill69