M693 - An unusual calcitic pseudomorph found associated with glacial marine deposits of Permian to Recent age.

Pseudomorphed from Ikaite, an unstable calcium carbonate that forms only under very specific conditions: very cold (almost freezing) water, organic-rich sediments that are highly alkaline, reducing and have a high hydrostatic pressure.

There are few localities in the world that have (or have had) the correct conditions for the formation of Ikaite and the after-ikaite pseudomorph, Glendonite.

Some of the specimens have a grey sandstone matrix that is naturally eroded into a smooth ball shape that the glendonite crystals appear to grow from.

Ikaite itself is an interesting compound. We cannot offer you specimens of it because it is unstable. It uses water molecules in its structure and if removed from the conditions it formed in, it decays and reverts back to calcium carbonate.