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Siderite is an iron carbonate of the calcite family. It is formed in the hydrothermal veins of medium- to high temperature. It is also a constituent main part of the sedimentary iron deposits. In these last deposits, it could be extracted as an iron ore if it were sufficiently abundant. Its crystals are rhombohedric, generally forming polycrystalline massive clusters.
The deposits are numerous: Hartz mountains in Germany but also in Bavaria, Palatinat, Westphalia; various English mines of Cornwall (Redruth, St Agnes...), in Panasqueira (Portugal) and into Bohemian (Príbram, Kutná Hora, Horní Slavkov..). And also in Peru, in Tatasi in Bolivia, in Morro Velho (Nova Lima, Minas-Gerais) in Brazil; in Broken Hill in Australia; in Tsumeb in Namibia. In USA, in Franklin, in the San Bernardino Co, with the mine of the Torch Mines in Wisconsin, like in the quarriess of Francon and of Mont Saint-Hilaire (Québec, Canada) without forgetting many recently opened mines in China. The gold mine of Iouriren in Morocco produced since 2007 of very beautiful samples.
In France, splendid crystals were found in the classical locality of Allevard, associated to quartz and more recently in St. Pierre de Mésage (Isère). Beautiful aggregates were also found in Peyrebrune (Tarn). It is common in the iron ore of Lorraine ("iron ore") and abounds in the Vosges, Auvergne, Brittany...
The type is not definable because it acts of a described old species before the conditions of deposit of the types were not defined.
Did you know? Siderite becomes magnetic when it is heated.
HISTORY : Name inspired from the Greek word "σιδεροσ" [sideros] meaning iron. Name given in reference to its chemical composition
Species first described in 1845 by Wilhelm Karl Ritter von Haidinger (1795-1871), Austrian geologist and mineralogist
Type-locality : undefined because species already known from the Ancients
ANCIENT NAME : Mine de fer spathique, fer carbonaté
CHEMICAL FORMULA : Fe CO3
CRYSTAL SYSTEM : Rhomboedric
COLOR : Yellow, brown, more scarcely gray or colorless
DIAPHANIETY : Opaque to translucent
LUSTER : Vitreous to pearly
STREAK : White
MORPHOLOGIE : Prismatic crystals, rhombohedra, scalénohedras, often massive
HARDNESS : 3,75-4,25
CHEMICAL CLASS: 3,932
DENSITY : V - Carbonates, nitrates and borates
GROUP : Calcite
STRUNZ CLASS BEFORE 2001 : 5/B.02-40
STRUNZ CLASS AFTER 2001 : 5.AB.05
