How to Make a Cobblestone Generator in Minecraft

Guide Java Bedrock

Quick answer: Place water and lava so flowing water touches a lava source from the side: where they meet, cobblestone forms instantly and forever. Mine it, and a new block regenerates in the same spot, giving infinite cobblestone.

What you need

1 water bucket
1 lava bucket
Any pickaxe
Optional: hopper + chest for auto-collection

Step by step

Gather 1 water bucket and 1 lava bucket. Lava is common in caves and the Nether; water anywhere.
Dig a trench 4 blocks long and 1 deep. Dig one more block down at one end (so water flows there).
Place the water source at the deeper end; it flows 1-2 blocks into the trench.
Place the lava source at the opposite end of the trench. Where the flowing water meets the lava source from the side, a cobblestone block appears.
Mine that cobblestone block with any pickaxe. A new one forms immediately in the same spot: infinite cobblestone.
Upgrade the design: put a hopper and chest under the mining spot to auto-collect, or mine from below with the block between you and the lava so drops never burn.
Stone and basalt variants: lava flowing DOWN onto water makes stone instead, and lava flowing over blue ice on soul soil makes basalt (1.16+).

Java vs Bedrock

Cobblestone generators work identically in Java and Bedrock: water flowing into a lava source from the side generates cobblestone, lava flowing down onto water generates stone, and lava over blue ice above soul soil generates basalt in both editions.

Versions: Classic (cobblestone generation since Indev)1.16 (basalt generators)

Frequently asked questions

Why does my generator make obsidian instead of cobblestone?

The water touched the lava SOURCE block directly from above or the lava touched the water source. Cobblestone only forms where flowing water meets the side of a lava source; water hitting a lava source head-on makes obsidian and consumes the lava.

Can you make an infinite stone generator?

Yes: let lava flow DOWN onto a water stream from above. That contact makes stone, which is great because stone (not cobblestone) is what stone bricks and repeaters need.

How do you make a basalt generator?

Place soul soil, put blue ice on top, and let lava flow over the blue ice. Basalt forms where lava meets blue ice above soul soil (1.16+).

Does a cobblestone generator ever run out?

Never, as long as the lava and water sources stay in place. Only the water touching the lava source directly (making obsidian) breaks it, and that only happens if you mine the wrong block.