Magma Blocks don't melt snow on top of them even though they burn you. This occurs even when snow is under your feet (and on top of the magma block.

What I expected to happen was...:
I would expect the snow to melt and not permanently stay on top (unless an external influence melts it)

What actually happened was...:
The snow did not melt.

Steps to Reproduce:
1. Place a magma block.
2. Wait for it to snow or place a snow layer on it.
3. Watch the snow not get melted.