User blog comment:Mrob27/Block type 130/@comment-5144400-20120830184743/@comment-4583259-20120831214047

I never found any on the surface but Scooter8pie did.

The stuff I found looked like light on the east, south, and west sides, and had a pretty dark appearance on the others. So it sounds like you found something new. This might be a difference of version 1.8 (which doesn't backup the game data, making it impossible for me to get maps).