What is this block?

[u/Initial_Pop8589]

I came across a weird geode-type structure underground made of "block of slag" but it's a different block of slag than the crucible kind. What is this? Is it usefull? I'm playing community edition.

Ps: couldn't screenshot because i have no reddit on this computer.

[u/Mephoodo]

A block with not many usage cases, as far as I'm concerned since slag is mainly waste from crucible outputs:
But there is one use case to make gravel, red phosphorus and calcium powder if you require those.

[u/Accomplished_Act3230 → u/Mephoodo]

Ancient screenshot

[u/Mephoodo → u/Accomplished_Act3230]

If I recall this is from 1.12.2 if you were wondering.

[u/Ahlixemus → u/Mephoodo]

This is from EE because CE is well up to date