Shock-wave transformations of fine-grained quartz dispersed in a silver matrix

Samples with porosities of $2$–$3$ and $13\%$ consisting of fine-grained quartz dispersed in a silver matrix were subjected to shock compression up to $28{,}~33{,}$ and $37$ GPa in planar recovery ampoules. In samples with a porosity of $2$–$3\%$, after purification from silver, along with amorphized quartz, a crystalline high pressure silicon dioxide phase was detected by powder X-ray diffraction, which differs from stishovite and presumably has a monoclinic lattice.