Siderite.

Siderite.

Van mine, Nr. Llanidloes, Central Wales ore field. This brecciated specimen is a mix of host rock, quartz, and siderite. The quartz, which is a gangue mineral at this mine is of a "sugary" nature, with no crystals to be seen. The siderite is not so solid as seen at other mines locally, but seems to be granular in nature, with just enough crystals to identify the mineral.