The École des Mines de Saint-Étienne possesses an important collection of wooden crystallographic models. Rehabilitation action was undertaken. Several series of Krantz models were identified by the logos and linked to catalogs. An exceptional element was discovered: a polyhedron with 170 facets, from the cubic system. We report on the digitalization work, followed by a description of two duplication methods: 3D printing and precision lost-wax vacuum casting.

Quartz is a very common form of almost pure silica. It can contain a small concentration of hydrogen-bearing defects whose nature is still debated. Here, we use a theoretical approach to unravel the atomic-scale geometry of these defects. Our findings help explain some important quartz properties.