赤铁矿

Rhombohedral \Rhom`bo*he"dral\, a. (Geom. & Crystallog.)
Related to the rhombohedron; presenting the form of a
rhombohedron, or a form derivable from a rhombohedron;
relating to a system of forms including the rhombohedron and
scalenohedron.

{Rhombohedral iron ore} (Min.) See {Hematite}.

{Rhombohedral system} (Crystallog.), a division of the
hexagonal system embracing the rhombohedron,
scalenohedron, etc.

Hematite \Hem"a*tite\, n. [L. haematites, Gr. ? bloodlike, fr.
a"i^ma, a"i`matos, blood.] (Min.)
An important ore of iron, the sesquioxide, so called because
of the red color of the powder. It occurs in splendent
rhombohedral crystals, and in massive and earthy forms; --
the last called red ocher. Called also {specular iron},
{oligist iron}, {rhombohedral iron ore}, and {bloodstone}.
See {Brown hematite}, under {Brown}.