THE MINERAL HEMATITE
Hematite is one of the most common minerals. The color of most
red and brown rock, such assandstone, is caused by small amounts of
Hematite. It is also be responsible for the red color of many
minerals such asGarnet,Spinel, and to some
extent,Ruby.Non-crystallineforms of Hematite may betransformations
of the mineralLimonitethat lost water, possibly due to heat.
Chemical FormulaFe2O3
CompositionIron oxide. May contain slight amounts of
titanium.
Variable Formula(Fe,Ti)2O3
ColorBlack, gray to silver gray, brown to reddish brown, red.
Some specimens areiridescent, and other are multicolored or banded
gray and dark red.
StreakRed to reddish brown
Hardness5-6
Crystal SystemHexagonal
3D Crystal Atlas(Click for animated model)
Crystal Formsand AggregatesCrystals occurs in thinplates, as
well as bundles of smallmicaceousplates, and in thinsplinters. Most
commonlymassive,mammilary,botryoidal,reniform,oolitic,stalactitic,
andradiating.Scalenohedralandrhombohedralcrystals occur, although
infrequently, anddendriticandrosetteforms are also found. Hematite
may also form as apseudomorphof other minerals, especially
asoctahedralcrystals ofMagnetite.
TransparencyOpaque
Specific Gravity4.9-5.3
LusterMetallic to dull
CleavageNone, but occasionally exhibits rhombohedral and
basalparting.
FractureUneven
TenacityBrittle
Other ID MarksHematite isparamagnetic, meaning it is slightly
attracted tomagnetic fields.
Complex TestsBecomes stronglymagneticwhen heated.
In GroupOxides;Simple Oxides
Striking FeaturesReddishstreak,hardness, crystal habits,
andparamagnetism
EnvironmentOccurs in all differentsedimentary,igneous,
andmetamorphicenvironments.
Rock TypeIgneous,Sedimentary,Metamorphic
Popularity (1-4)1
Prevalence (1-3)1
Demand (1-3)1
