Ferroelasticity in palmierite-type(1 - x)Pb(PO) xPb(AsO).

Lead phosphate-arsenate Pb(P As O) undergoes an improper ferroelastic phase transition from a rhombohedral paraphase [Formula: see text] to a monoclinic ferrophase [Formula: see text] leading to distinct twin boundary patterns. On cooling compounds with x larger than 0.8 undergo further transitions to monoclinic low-temperature phases, whereas the composition with x  =  0.

Evidence for direct impact damage in metamict titanite CaTiSiO₅.

We have measured the dose dependence of the degree of amorphization of titanite, CaTiSiO(5). Titanite is an often metamict mineral which has been considered as a matrix for the encapsulation of radiogenic waste, such as Pu. The amorphous fraction p of geologically irradiated samples (ages between 0.