This is a light lavender 2.8 cm anhydrite crystal sitting perched on top of a parrallel-growth aggregate of probertite crystals. Beautiful colour and aesthetic placement – hard to ask for better.
Anhydrite is notoriously difficult when it comes to detecting cleaves – a cleavage plane and a crystal face can look virtually identical (not unlike carbonate species such as rhombohedral rhodochrosites and magnesites – or, for that matter, the blue fans of anhydrite from Mexico, which naturally end in feathery tips, while flat “faces” at the top are in fact cleavage faces). From this find, I have seen anhydrite faces I’d swear were cleaved, but then with probertite or other anhydrite on top, confirming that they are not. This specimen is more complex in shape than some others from the locality. I’ve included photos from various angles so you can see what I mean. I’ve examined it at length, and the only spot of the main crystal I am certain is cleaved is on the backside near the top of the crystal (there are other smaller cleaved anhydrites on the piece). To me, this is a great display specimen of anhydrite.
About these Anhydrite/Probertite Specimens
These excellent specimens of anhydrite and probertite were found in a pocket at the Kohnstein Quarry, Niedersachswerfen, Nordhausen, Harz, Thuringia, Germany. The anhydrite crystals are amazing – euhedral, very pale lilac, translucent to transparent. I am told that although they are encountered at this locality once in a while, this is only the third time in the last 30 years, so it is not a common occurrence.
Anhydrite is one of those common minerals that is incredibly hard to obtain in display specimens, other than the relatively common light blue Mexican anhydrite fans. Euhedral, well developed crystals of any decent size are rare.
Probertite is a relatively rare borate mineral that occurs as transparent, colourless, heavily striated, lustrous crystals. Atother world localities it usually occurs as radiating aggregates of acicular or columnar crystals, coarser crystal aggregates are uncommon and euhedral terminated crystals much more so.