Oil

Oil is a useful resource in The Blockheads that has multiple sources.

Appearance
Once in a blockhead's inventory, oil looks like a drop of black liquid.

When found underground, an oil deposit looks like a black blob on a block of limestone.

Where Found
Oil can be found as part of underground limestone veins. Mining it works best with a pickaxe, producing three units instead of one. It can often be found near or under mountains.

It can also be created by using a press on flax or sunflower seeds, producing two units of oil per seed.

Crafting
Oil is essential for making oil lanterns, steel lanterns, mixing benches, paintings, and paint.