This specimen contains marcasite and bladed barite. The barite has blue coloration and bladed formation and the aggregated sharp marcasite makes for a beautiful association of minerals.
Barite, commonly spelled baryte, is well-known for its great range of colors and varied crystal forms and habits. It is a heavy mineral consisting of barium sulfate, and typically has the chemical formula of BaSO4. The barite group consists of baryte, celestine, anglesite and anhydrite. It's generally white to colorless and is the main source of barium.