THE MINERAL HEMATITE
- Chemical Formula: Fe2O3, Iron Oxide
- Class: Oxides and Hydroxides
- Group: Hematite
- Uses: Very important ore of iron, as a pigment and as mineral specimens.
- Specimens
Hematite has several varieties, each with their own unique names.
- Hematite Rose is a circular arrangment of bladed crystals giving the appearance of the flower of a rose.
- Tiger Iron is a sedimentary deposit of approximately 2.2 billion years old that consists of alternating layers of silver gray hematite and red jasper, chert or even tiger eye quartz.
- Kidney Ore is the massive botryoidal form and gives the appearance of lumpy kidney-like masses.
- Oolitic Hematite is a sedimentary formation that has a reddish brown color and an earthy luster and is composed of small rounded grains.
- Specularite is a micaceous or flaky stone that is sparkling silver gray and sometimes used as an ornamental stone.
Hematite is sometimes used in jewelry, either as black reflective stones or as a jewelry piece itself (such as a ring). Some jewelry is marketed as "magnetic hematite". I believe that is more likely another iron oxide, magnetite.
PHYSICAL CHARACTERISTICS:
- Color is steel or silver gray to black in some forms and red to brown in earthy forms. Sometimes tarnished with iridescent colors when in a hydrated form (called Turgite).
- Luster is metallic or dull in earthy and oolitic forms.
- Transparency: Crystals are opaque.
- Crystal System is trigonal; bar 3 2/m
- Crystal Habits include tabular crystals of varying thickness sometimes twinned, micaceous (specular), botryoidal and massive. also earthy or oolitic.
- Cleavage is absent. However, there is a parting on two planes.
- Fracture is uneven.
- Hardness is 5 - 6
- Specific Gravity is 5.3 (slightly above average for metallic minerals)
- Streak is blood red to brownish red for earthy forms.
- Associated Minerals include jasper (a variety of quartz) in banded iron formations (BIF or Tiger Iron), dipyramidal quartz, rutile, and pyrite among others.
- Notable Occurrences especially nice specimens come from England, Mexico, Brazil, Australia and the Lake Superior region.
- Best Field Indicators are crystal habit, streak and hardness.
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