Beautiful!
Back in the days when I made stained glass art, there was a type of glass that looked like that.
IIRC, it was made by spreading glue over the glass sheet as it hardened, and then the glue would contract and form that type of feathery shape and pull the glass surface with it.
Ah, here it is

I remember when I was a kid growing up in Derbyshire it'd be so cold in our house (we had just a single coal fire in one room) that there'd be frost patterns inside the bedroom windows. I've always loved those patterns.

Beautiful!

that is really cool. it doesn't get very cold in south central PA anymore so i rarely see that kinda stuff anymore.

Just ran out to put my car in the garage as there's an ice storm starting here. Those crystals are pretty but I don't want to have to scrape them off my windshield.