Sekka Zusetsu: A Book of Snowflakes (1832) (publicdomainreview.org)

Big fan of the bottom right snowflake on this page: https://pdr-assets.b-cdn.net/collections/japanese-snowflake-...

Transferring each snowflake by hand with tweezers is insane, what a feat

It appears that the author of this work invented the word 雪華 (sekka); it originates in that book. Other than that, a snow crystal is just called ゆきの結晶 (yukinokesshō).