Titanium dioxide occurring in acute octahedral crystals.
Titanium dioxid, crystallizing within the tetragonal system, the fundamental and commonly happening form being an acute square octahedron (whence the name); anatase.
A meteoric iron with octahedral framework, which is typically distinctly marked by the lamellæ of kamacite, tænite, and plessite, noticed in the Widmannstättian figures. Most iron meteorites fall-in this course. See meteorite.