Siderite is Iron carbonate FeCO3 This specimen was collected from Marine colliery waste heaps in Ebbw Vale many years ago. The waste heaps and all sign of the colliery have long disappeared. The clay ironstone bands in the south Wales coal field which are the origin of the specimen, date from the upper Carboniferous period. The specimen is brecciated ironstone with numerous vhugs which are filled with small golden brown platey crystals of siderite.