Quartz crystal

While this α quartz (SiO₂) crystal is not museum quality, it does show most of the diagnotic visual properties of quartz at a crystal level. The crystal is six-sided (two trigonal prisms), has a pyramidal termination at the top, is pale coloured and transluscent, and has the typical striations perpendicular to the Z-axis (or C-axis) on the prism faces. Complications include that the crystal is twinned, so more than a single crystal is present, some of the surfaces are fractures, and some of the surfaces are impressions of neighbouring crystals it was prised from.