This is one of the most unique specimens I have yet seen from Yindu—I have no idea when it was found, nor (to reiterate my use of the word “unique”) have I seen any others from this pocket. This has a very hefty spinel twin, it has a purple core surrounded by a vividly blue ring, all this is surrounded by a saturated green layer. The outer layer is fluorescent.

This would be less unusual from Erongo, a locality known for its large spinel twins and this green color (though I have yet to see a green twin...) however this clearly is not from that location-- the parallel purple cores are a hallmark of these oddly elongated fluorites crystals from Yindu.  

While already impressive without special lighting, backlighting reveals the internal features. I have seen purple spinel twins from this mine—in fact I offered some here a few months ago, but those tended to be flatter and none even came close to this length, width, and they had totally different color (purple). 

Terrible pictures, video available on request.