Calcite with Pyrite

This superb miniature Calcite is from the Příbram Mining District in the Czech Republic.  Close examination shows it is composed from multiple successions of mineral deposition, each phase manifesting as a different habit, colour or lustre.  Formed around a central core of granular, sooty-black sulphides or Mg/Mn minerals, the first phase of Calcite forms scalenohedral 'dog-tooth' crystals to over 2 cm tall which radiate outward in a hedgehog-like fashion.  These crystals have then been coated in dull brick-red Calcite micro-crystals with a matt lustre, followed by burnt candy-red lustrous Calcite crystals, all approximately 1 mm in length and aligned epitaxially to the scalenohedrons' major axes.  A little mound of micro-crystallised Pyrite is attached not far above the base.  A beautiful and fascinating Calcite from Příbram.