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Siderite
Current inventory:  0 gems
 

Chemistry:  Fe²⁺(CO₃)   [Iron Carbonate]

Discovered in 1845;   IMA status: Valid (pre-IMA; Grandfathered).
The name Siderite is from the Greek word sideros meaning iron due to its high iron content (48%).

Classification

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/B.02-40

Nickel-Strunz 10th Ed. ID:

5.AB.05

5 : CARBONATES (NITRATES)
A : Carbonates without additional anions, without H₂O
B : Alkali-earth (and other M²⁺) carbonates

Related to:

Calcite Group: Vaterite, Calcite, Magnesite, Siderite, Rhodochrosite, Smithsonite, Spaerocobaltite, Gaspeite, Otavite. Magnesite - Siderite Series and Rhodochrosite - Siderite Series.

Crystal Data

Crystallography:

Trigonal - Hexagonal - Scalenohedral

Crystal Habit:

Commonly crystallized, typically rhombohedral [1011] to steep scalenohedral [2131], prismatic [1010], [0001], with additional minor forms, to 25 cm; fibrous, stalactitic, spherulitic, cleavable, fine-grained massive.

Twinning:

Uncommon on [0112], lamellar; rare on [0001]

Physical Properties

Cleavage:

[1011] Perfect, [1011] Perfect, [1011] Perfect

Fracture:

Conchoidal, Irregular/Uneven

Tenacity:

Very Brittle

Hardness (Mohs):

3.75 - 4.25

Density:

3.96 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioacitve

Other:

Slightly soluble in water.

Optical Properties

Color:

Yellowish Brown, Brown, Gray, Yellowish Gray, Greenish Gray

Transparency:

Transparent, Translucent

Luster:

Vitreous, Pearly, Silky

Refractive Index:

1.633 - 1.875  Uniaxial ( - )

Birefringence:

0.215 - 0.242  (very high)

Dispersion:

Strong

Pleochroism:

None

Occurances

Geological Setting:

A common component of bedded sedimentary iron ores and metamorphic iron formations; in hydrothermal metallic veins; rarely in granite and nepheline syenite pegmatites; in carbonatites; authigenic, and in concretions.

Common Associations:

Barite, Fluorite, Pyrite, Quartz

Type Locality:

n/a

Year Discovered:

1845

View mineral photos:

Siderite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Siderite is a rare and beautiful gem that is difficult to facet due to its perfect rhombohedral cleavages and brittleness. It is in a mineral series with Rhodchrosite (MnCO₃) and Calcite (CaCO₃). It is found at several locations around the world, but gem quality crystals are somewhat rare. The main sources are Mont Sainte Hilaire, Quebec, Canada (brown) and Panesqueria, Portugal (green).
 

  
Siderite gems for sale:

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