Mineral description : Ankerite

Chemical formula	CaFe(CO3)2
Hardness	3.5
Density	3.2
Color	Light yellow to brown.
Crystal form	Trigonal. Romboedric crystals or grainy masses.
Luster	.
Description	A rare mineral in Sweden. Occurs as crystals with quarts and calcite or as veins in some sulphide mines.
Habitat	.
Alternative name	Brunspat
Associates	Quartz and calcite.
Notes	Reacts with cold hydrochloric acid under release of gas, not as violent as calcite. The density of ankerite separatest it from dolomite (2.8-2.9) and siderite (3.7-3.9). After heavy firing, ankerite and siderite 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.
Locations	The best locations are : Knolle mine, Ånimskogs socken, Älvsborgs län. As crystals in a mix of quarts and calcite. Pahtavaara sulphide mine, Jukkasjärvi, Lappland. As veins.

To carbonates index.

Mineral group index.

Main index.

If you have some questions, suggestions or comments you are welcome to write me a line or two.