Small snowflake, around 2mm. It is slightly melted and definitely worse than perfect photo by Pam Eveleigh:
Eveleigh-snow12-8900
10 serial shots averaged to boost signal-to-noise ratio. Background: dark woolen fabric, natural light (gray clouded sky), external optics Helios 44M-5, march 2013, Moscow.
Prints available at Artist website (mirrors at Pixels and FineArtAmerica).
This tiny and unusual crystal was chosen as cover for music disk "Asylum Benefits EP" by Laurent Memmi, a French drone / ambient music producer:
Here you'll find other triangular snowflakes - Enigma and Emerald:
If you want to see more snowflakes, you can browse through all snowflake pictures.
Here you'll find snowflake photo wallpapers in numerous resolutions and screen proportions, up to Ultra HD 4K.
And here is article about snowflake macro photography.