Description
Hematite's popularity in jewelry was at its highest in Europe
during the Victorian era, and has since seen a strong
resurgence inNorth America, especially in the western United
States. Certain types of hematite or iron oxide rich clay,
especially Armenian bole has been used in gilding.
Hematite is also used in art such as intaglio engraved
gems. Hematine is a synthetic material sold
as magnetic hematite.
Hematite, also spelled as haematite, is
the mineral form of iron(III) oxide (Fe2O3),
one of several iron oxides. Hematite crystallizes in
the rhombohedral system, and it has the
same crystal structure
as ilmenite and corundum. Hematite and ilmenite form
a complete solid solution at temperatures above **0 °C.
Hematite is a mineral, colored black to steel or silver-gray, brown
to reddish brown, or red. It is mined as the main
ore of iron. Varieties include kidney
ore, martite (pseudomorphs after magnetite), iron
rose and specularite (specular hematite).
While the forms of hematite vary, they all have a rust-red
streak.
Hematite is harder than pure iron, but much more
brittle. Maghemite is a hematite-
and magnetite-related oxide mineral. Huge deposits of hematite
are found in banded iron formations. Grey hematite is
typically found in places where there has been standing water or
mineral hot springs, such as those in Yellowstone
National Park in the United States. The mineral
can precipitate out of water and collect in layers at the
bottom of a lake, spring, or other standing water. Hematite can
also occur without water, however, usually as the result
of volcanic activity.
Clay-sized hematite crystals can also occur as a secondary mineral
formed by weathering processes in soil, and along
with other iron oxides or oxyhydroxides such as goethite, is
responsible for the red color of many tropical, ancient, or
otherwise highly weathered soils.
