Calcite from Wenshan Mine, Wenshan City, Wenshan, Yunnan, China

A rather remarkable specimen consisting of a calcite crystal with very striking twists and turns. It starts off with a very regular helical stretch (lower half), before making a complete U-turn and doubling back on itself in the same plane, ending in a beautifully clear tip. Interestingly, it really rings with a beautiful clear tone like a tuning fork when you carefully give it a tap with your finger, owing to the fact it's all a single continuous crystal. Additionally, it has a thin hollow tube running through its core along its full length, something I have observed in similar specimens from this mine as well; potentially this phenomenon might have played a role in how these curious helictites were formed.

The specimen is no longer in my collection.