Neutron emission measurements by means of helium-3 neutron detectors were performed on solid test specimens during crushing failure. The materials used were marble and granite, selected in that they present a different behaviour in compression failure (i.e., a different brittleness index) and a different iron content. All the test specimens were of the same size and shape. Neutron emissions from the granite test specimens were found to be of about one order of magnitude higher than the natural background level at the time of failure.
@article{arxiv.0903.3104,
title = {Piezonuclear neutrons from fracturing of inert solids},
author = {F. Cardone and A. Carpinteri and G. Lacidogna},
journal= {arXiv preprint arXiv:0903.3104},
year = {2009}
}