Hematite, an iron oxide mineral, is well-known for its striking metallic luster and deep red to black colorations. Appearing in various geologic formations, this mineral occur in multiple forms with different properties. Two of these are earthy hematite and mineral hematite.
While they share the same chemical composition, the differences in their appearance, formation processes, and applications are significant. Hematite used by the painter may be unsuitable for the potter, and that of the potter doesn't fulfill the needs of the carver.
Hematite ranges in hardness from soft to moderately hard (about 1 to 6 on the Mohs Hardness Scale). Whatever the specimen’s color, hardness or luster, hematite will always leave a brick red-colored streak, a distinctive diagnostic property.
What is Hematite?
Chemically, hematite is composed of iron (III) oxide, with the formula Fe₂O₃. This mineral is a primary ore of iron. Its properties and versatility attract the attention of geologists and mineralogists, artisans, jewelers, and collectors.
Earthy Hematite
Characteristics
Earthy hematite is characterized by dull luster and rough texture. This hematite appears in shades of brown, reddish-brown, or dark gray. It often has a powdery appearance, like soil or clay. The earthy texture can be caused by breakdown due to weathering.
Formation
Earthy hematite forms through a process of weathering and oxidation of iron-bearing minerals. It's commonly found in sedimentary environments, where iron is leached from parent rocks and precipitated in soils or sediments.
This form often retains moisture, found within sedimentary rocks, soil or iron-rich clays. Earthy hematite is in more superficial deposits compared to its mineral counterpart. There are many shades of red often in balance with yellow ocher limonite or purple-red manganese.
Uses
Due to its powdery texture and coloration, earthy hematite finds its applications in various sectors, including:
Pigment Production: Ground earthy hematite is used as a pigment in paints, cosmetics, and ceramics, providing a warm hue and opacity.
Soils and Landscaping: It is often used in gardening and landscaping as a soil amendment or decorative aggregate.
Jewelry: Although less common than its more lustrous counterpart, earthy hematite beads are sometimes used in jewelry.
Mineral Hematite
Characteristics
In contrast, mineral hematite is known for its metallic, shiny appearance, often having a brilliant mirror-like luster when polished. This form tends to be found in distinct crystal shapes, often occurring as tabular crystals or in masses.
It ranges in color from striking red to silvery black, making it highly sought after for its aesthetic value. Mineral Hematite hovers at 5.5 - 6 on the Mohs hardness scale, making this a fine stone for carvers but a unnecessary difficulty for rustic pigment grinders.
Formation
Mineral hematite typically forms in igneous and metamorphic rocks, through igneous processes or the metamorphism of iron-rich minerals. During these processes, iron is precipitated from hot hydrothermal fluids, allowing for the formation of well-defined crystals.
Uses
The uses of mineral hematite include:
Iron Ore: Given its high iron content, mineral hematite is a significant source of iron, crucial for steel production and other industrial applications.
Jewelry: Its shinier finish and ability to take a high polish make it a popular choice in jewelry design.
Decorative Stones: The beautiful aesthetics lead to its use in decorative stones and sculptures.
Key Differences at a Glance
Aspect | Earthy Hematite | Mineral Hematite |
Appearance | Dull, powdery; often brown or reddish | Shiny, metallic; red to black |
Texture | Rough, earthy | Smooth, often crystalline |
Formation Process | Weathering of iron-rich minerals | High-temperature hydrothermal processes |
Common Uses | Pigments, soil amendments, jewelry (less common) | Iron ore, jewelry, decorative stones |
Because hematite is so variable in color, crystallization and hardness, unravelling the secrets of this rock can keep the hobbyist busy at least until lunch time. Unlike sister stone magnetite, hematite is not magnetic. Magnetized hematite is generally synthetic. Pretty, though.
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