the most important iron ore, has an extremely variable appearance.
It can be black, gray, silver, brown, or red; its luster can
range from metallic to earthy, and its forms include micaceous,
massive, crystalline, fibrous, botryoidal, and others. All
Hematite, however, produces a characteristic
red streak when rubbed across unglazed white
porcelain, which is why Hematite gets its name from the Greek word for blood.
large Hematite deposits formed in sedimentary environments, but
Hematite is also found in metamorphic and igneous rocks. NASA
even discovered Hematite on Mars! Many rocks and
the Martian surface contain Hematite, explaining why Mars is
called the "Red Planet".
The Hematite specimens on this page may be "out of
this world," but they're from Morocco,
not Mars. They display Hematite's classical botryoidal habit, a
mineral habit in which the mineral displays a globular external form
resembling a bunch of grapes. Botryoidal comes
from the Greek word meaning (you guessed it!) "having the form of a
bunch of grapes."