Siderite
A variety of Calcite Group
What is Siderite?
Siderite is an economically-important mineral that is often mined as an ore of iron. The mineral is also sometimes called "Chalybite", especially when it comes from Cornwall, England. Siderite crystals, which are typically tan, grey, yellow, or honey-colored, are soft and brittle - although the occasional exceptional specimen may be carved into a gemstone, sought after only by highly specialized collectors.
Etymology & Origins
It takes its name from the Greek word σίδηρος sideros, "iron". It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus.
Uses & Applications
Siderite can be used as an ore for iron, though it is only found in a few places in the world. Often, it is processed into a form called "pig iron" that is extremely strong and heat resistant, making it useful to create furnaces. When ground into a powder, it can also be used to create brown pigments.
Healing Properties
Siderite is believed to provide positive energy and can help enhance one's career and provide stability in employment. It works on all of the chakras and is said to enrich every aspect of the mind, body and spirit. Carry it in your pocket to keep all the chakras aligned.
Optical Properties
- Refractive Index
- 1.633-1.875
- Birefringence
- 0.24
- Pleochroism
- None
- Optical Character
- Uniaxial negative
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Siderite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Siderite Localities Map
See where Siderite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Associated Chakras
Key Characteristics
Formation of Siderite
Siderite is commonly found in hydrothermal veins, and is associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in shales and sandstones, where it sometimes forms concretions, which can encase three-dimensionally preserved fossils. In sedimentary rocks, siderite commonly forms at shallow burial depths and its elemental composition is often related to the depositional environment of the enclosing sediments. In addition, a number of recent studies have used the oxygen isotopic composition of sphaerosiderite (a type associated with soils) as a proxy for the isotopic composition of meteoric water shortly after deposition.
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Quick Facts
Physical Properties
- Color
- Yellowish-brown to greyish-brown, pale yellow to tannish, grey, brown, green, red, black, sometimes, nearly colourless, tarnished iridescent at times, colourless to yellow, yellow-brown in transmitted light
- Hardness (Mohs)
- 3.5 - 4.5
- Density
- 3.932 g/cm³
- Streak
- White
- Luster
- Pearly, Vitreous, Silky
- Crystal System
- Trigonal
Chemical Properties
- Chemical Formula
- FeCO3
- Elements
- C, Fe, O
Also Known As
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Siderite FAQs
How do I identify Siderite?
Siderite can be identified by its hardness of 3.5 - 4.5 on the Mohs scale, Yellowish-brown to greyish-brown color, Pearly, Vitreous, Silky luster, Trigonal crystal system. Look for these key characteristics when examining specimens.
What color is Siderite?
Siderite typically appears in Yellowish-brown to greyish-brown, pale yellow to tannish, grey, brown, green, red, black, sometimes, nearly colourless, tarnished iridescent at times, colourless to yellow, yellow-brown in transmitted light. Color can vary depending on impurities and formation conditions.
How hard is Siderite?
Siderite has a hardness of 3.5 - 4.5 on the Mohs scale. This gives it moderate hardness.
What is the formation of siderite of Siderite?
Siderite is commonly found in hydrothermal veins, and is associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in shales and sandstones, where it sometimes forms concretions, which can encase three-dimensionally preserved fossils. In sedimentary rocks, siderite commonly forms at shallow burial depths and its elemental composition is often related to the depositional environment of the enclosing sediments. In addition, a number of recent studies have used the oxygen isotopic composition of sphaerosiderite (a type associated with soils) as a proxy for the isotopic composition of meteoric water shortly after deposition.
