Ground up pumice with a portland cement binder. Good insulation qualities because of the porosity of the pumice. Very nice material for building in at least some places.
Am I correct in thinking that it isn't especially good for building in areas with winters below freezing and a fair amount of humidity because of the possibility or probability of cracking or exfoliation (caused by expansion of ice upon freezing)? There seems to be a fair amount of information around on the subject of pumice-crete, but nothing that addresses this particular question. It's pretty obvious that the stuff ISN'T often used in the eastern US, but I wonder if it's really a matter of not being an appropriate building material.
Just curious, 'Sporky'