Their principal iron mineral is hematite, although the English ores also contain considerable iron carbonate or siderite.
siderite, or spathic iron ore, FeCO3, crystallizes in the rhombohedral system and contains 48.28% of iron.
Quartzite (instead of limestone) is an unusual locus of replacement ores, and siderite is an unusual gangue.
The Bilbao ores consist mainly of siderite, which near the surface has altered to large bodies of oxide minerals.
This siderite is specially interesting on account of its distinctly metallic character.
Carbonate of Iron, or siderite, occurs in a few localities, the ore produced in Ohio being almost wholly of this kind.
This compound occurs in nature as siderite, and is a valuable ore.
This is one of the ordinary stony meteorites, and is thus contrasted with the Rowton siderite which we have just been considering.