I don't think I've ever seen something like that!!
I've seen something like this before, but not often, and then it was caused by freezing rain.
In this case, the explanation must be something else, for as far as I can remember, it didn't rain at all the days I was climbing Pequeño Alpamayo.
In fact, I can only recall one short spell of light rain in the whole five weeks that I was in Bolivia. Sure, it's a bit colder in winter, but still, excellent climbing conditions!
Basically, winter on the altiplano is dry. Very, very dry. A whole lot different from what's happened in La Paz a few days ago :-(. Completely foreseeable, but sad nonetheless.
This can happen when rime or hoarfrost partially melts in the sun, then refreezes overnight. The tiny white frost crystals merge into a single glassy matrix while keeping most of their shape.
Guess the wind direction when these ones were originally deposited:
Sometimes the process repeats: rime on ice
Sure, but I wonder how many times it turns out to be something so regular and so exquisitely beautiful...like a Swarovsky creation...