The density and porosity of lunar rocks

Accurate lunar rock densities are necessary for constructing gravity models of the Moon's crust and lithosphere. Most Apollo-era density measurements have errors of 2-5% or more and few include porosity measurements. We report new density and porosity measurements using the bead method and helium pycnometry for 6 Apollo samples and 7 lunar meteorites, with typical grain density uncertainties of 10-30 kg m(-3) (0.3-0.9%) and porosity uncertainties of 1-3%. Comparison between igneous grain densities and normative mineral densities show that these uncertainties are realistic and that the helium fully penetrates the pore space. Basalt grain densities are a strong function of composition, varying over at least 3270 kg m(-3) (high aluminum basalt) to 3460 kg m(-3) (high titanium basalt). Feldspathic highland crust has a bulk density of 22002600 kg m(-3) and porosity of 10-20%. Impact basin ejecta has a bulk density of 2350-2600 kg m(-3) and porosity of similar to 20%. Citation: Kiefer, W. S., R. J. Macke, D. T. Britt, A. J. Irving, and G. J. Consolmagno (2012), The density and porosity of lunar rocks, Geophys. Res. Lett., 39, L07201, doi: 10.1029/2012GL051319.