A beautiful enigma of a snowflake saved for Christmas Day. I love these exotic crystals, partly because they are so unconventional and more importantly that they are so far to figure out!
You’re looking “arrowhead” snowflake formations here, though the exact origin is somewhat obscured in the middle. What’s an arrowhead snowflake? They are often seen with repeating angles just less than 90 degrees, growing in a line. The trademark for these crystals is that there is a line running down the middle, a ridge of sorts, connecting two halves together. These two halves are molecularly unique crystals, connected together with a “zipper” that would connect two unique-but-similar fabrics.
Can you spot these zippers? There’s an easy one in the upper right. The abundance of 78-degree angles gives away these formations as well, with another less obvious zipper in the lower left, and a few others can be spotted if you know what to look for. This zipper is the unlikely molecular “glue” that combines two normal crystal lattices that form on either side of it. Water molecules usually for a symmetrical hexagonal lattice, but there are other “accidental” patterns that can arise from initial nucleation. There are at least three arrowhead varieties on a molecular level, but these initial molecular mishaps also give way to “crossed plate”-type snowflakes.
I have never seen a clean and orderly starting point to arrowhead crystals – there are usually clusters of unrecognizable shapes, with some bullet-type columns thrown in for good measure. This snowflake is no exception, with a clearly-identifiable capped bullet in the middle. Once the snowflake grows beyond this initial mess, you’ll start to see that “zipper” show up in what could be considered the branches of this snowflake.
Look very closely, and you’ll also see that these branches are not common column shapes, but are actually “scrolls”, wrapping around but not completing a hexagonal prism. Best examples are seen at the very top and in the lower right. Scrolls can be seen when you shift from plate-type growth back to column-type growth (not very common!) as well as when you get an outlandish jumble of crystal types as we see here.
Undoubtedly a rarity, often seen forming in warmer temperatures that produce column and needle-type snowflakes as well as small plates. These snowflakes might not get as much fanfare as a perfectly symmetrical gem, but I like them even more for the obscurities they reveal.
Merry Christmas, everyone!