Hydrogrossular after Wadalite (Achtaragdite)

specimen number:
2063210

location:
Vilyui River Basin, Mirninsky, Sakha, Russia

description:
Classic Russian pseudomorph specimen, at one time these were referred to by the now discredited name achtaragdite. This is basically hydrogrossular-chlorite replacing what is quite possibly the mineral wadalite. This way sharply formed and in great condition. The specimen comes with a previous label from the collection of Ray DeMark.

Achtaragdite is an uncommon pseudomorph traditionally described from Siberia, consisting primarily of hydrogrossular, chlorite, and carbonate minerals. It often preserves the crystal shape of a precursor mineral, which modern studies suggest may be wadalite or another related hydrogarnet species. Because the original protomineral has undergone extensive alteration and replacement over time, its exact primary composition remains a subject of ongoing mineralogical study, though it typically exhibits a distinct pseudomorphic form.

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