Golden Calcite (medium)

Superb rhombohedral crystals of Golden Calcite occur in cavities in large concretions in the 70-million-year-old ancient Pierre Shale Seaway on Elk Creek, South Dakota. The crystals can be yellow, orange and amber colored; are quite prolific; and are often associated with Golden Barite and Selenite crystals. The concretions were first formed by ancient Mollusks that perished on the seafloor and were rolled into small fossil balls by Ocean currents. Later, nearby Meteorite impacts sent large Tsunami waves down the seaway rolling the small fossil balls into the larger septarian concretions we find exposed today.

The smaller rhombohedral crystals forming the Golden Calcite, came from the dissolved shells of the ancient sea life that once thrived in this warm shallow seaway. During the last Ice Age 40,000 years ago, erosion exposed the concretions and allowed Pleistocene meteoric waters to dissolve, transport and precipitate the calcium carbonate to form the crystals we find in the septarian concretions today. The Golden Calcite crystals fluoresce a bright yellow-white under shortwave ultraviolet light.