Oyster Selenite, is formed by natural cracks – first from weaker chemically bonded areas (due to impurities or faster dehydration) then weathering from the expansion of heat and also by cold from when water then finds it’s way into these little cracks and then freeze.

These cracks are then left exposed for a time to the surface (where the weathering is also happening) and where either calcium carbonate (calcite) and or desert lichens and algae creep in and grow for a while. They then eventually decompose and leave behind what’s left of them in the form of detritus carbon (longer carbon chains from either calcite or lichens or algae generally are grey to black). Other cracked areas are just filled in from lite fine particles of desert sand dust. Later on, as the desert weather exposes and then sometimes reburied these selenite crystals, water chemistry dissolves some selenite off of surrounding areas and precipitates back crystals into these grey cracks and heals it up. other areas of grey don’t get re-crystalized at all, but are still trapped inside and look amazing all the same.

The whiter areas are formed mostly just from the weaker crystal growth or from the weathering process, but where it was not wide enough for algae or lichens to grow.

Green areas in these are where there are recently alive or very alive algae and/or lichens OR from chlorite particles in the nearby clay.