When crafting polished scoria or polished dark scoria, you only get a single polished block from the recipe. This is contrary to all other polished stone recipes both in Quark and in Vanilla Minecraft.

JEI Polished Scoria Crafting Recipe:

JEI Polished Marble Crafting Recipe:

This does not seem intended, and I have not seen it mentioned anywhere else, so I figured I would report it as an issue.

This is not a quark feature.