Thick Soul Snow is a block added by the Soul Forest Mod. Is almost identical to the Soul Snow, but has a very clear difference: you can only walk through the Soul Snow block and not through the Thick Soul Snow block. As you can't look through the block it i very difficult to see which are the Soul Snow blocks and which are the Thick Soul Snow blocks.
Thick Soul Snow can be used to craft Ice Bricks, together with Soul Snow, Frozen Rods and Frost Shards.
Thick Soul Snow only spawns in the Frost Caves Biome in the Soul Forest Dimension, which makes that biome a very dangerous biome. You might just fall down a long way as theres suddenly a very little ground underneath the Soul Snow Blocks. Thick Soul Snow is the 2e layer of blocks on a platform from haflway up the dimension and is the top layer of blocks in the bottom section of the dimension.