About two-thirds of the ore mined is clayey siderite.
Siderite nodules from the Coseley fossil assemblage contain an abundant, diverse, and well preserved coal measures flora.
Siderite, or spathic iron ore, FeCO 3, crystallizes in the rhombohedral system and contains 48.28% of iron.
The clayey siderite of the British coal measures is called " clay band," and that containing bituminous matter is called " black band."
The larger part of Lorraine belongs to France, but the German part nossesses great mineral wealth in its rich layers of ironstone (siderite) and in the coal-fields of the Saar.
The most important British ore deposit is the Lower Cleveland bed of oolitic siderite in the Middle Lias, near Middlesborough.
They are four important iron ores, magnetite, haematite, limonite and siderite, and one of less but still considerable importance, pyrite or pyrites.