Siderite with Calcite

This Siderite, from the Příbram District in the Czech Republic, forms an almost circular, slightly domed specimen, covered with broad, gently curving blades of typically 2 cm across and of a characteristic honey-tan.  This colour is largely masked by a pervasive coating of Calcite micro-crystals as sub-mm colourless glassy rhombs which impart a light grey speckled film over the Siderite.  To one end, the Siderite is completely coated with drusy mounds of opaque creamy-white Calcite, built from sub-mm crystals.