Mineral description : Siderite

Brown siderite with actinolite from Pahtavaara gold mine, Finland. (size 4x3.5x1 cm)

Chemical formula	FeCO3
Hardness	4-4.5
Density	3.7-3.9
Color	Opaque, yellow, white or grey. Brown on weathered surfaces.
Streak color	White to yellow.
Crystal form	Trigonal. Romboedric crystals. Also as massive, botryoidal, earthy, fibric or grainy.
Luster	Glas to pearl.
Description	.
Habitat	Siderite is created in hydrothermal environments, in sediments together with organic material or below the oxidising zone in mines.
Alternative name	Järnspat
Associates	Calcite, galena, zinkblände, pyrite, kopparkis, chlorite, ankerite.
Notes	Reacts with warm hydrochloric acid under release of gas, not as violent as calcite. The density of siderite separates it from dolomite (2.8-2.9) and ankerite (3.2). After heavy firing, siderite and ankerite becomes magnetic, dolomite and calcite does not. If a carbonatic sample is wetted with a weak acid solution of K3Fe(CN)6, some carbonates gets a blue color (Turnbulls blue) : calcite none, dolomite none, ankerite light blue, siderite dark blue.
Localities	The best locations are : Mossgruvan. Grängesberg. Värmskogsgångarna, Värmland. Norbergs minefield. Yxsjöberg scheelite deposit.

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