nocware
Quick answer
- Ruined portals are broken Nether portals found in almost every biome.
- They come with a chest of gold items, obsidian and sometimes a
Flint and steel. 
Crying obsidian in the frame stops it working. Replace it with normal obsidian.
A ruined portal is a lucky find early in a world. It can save you mining obsidian and get you to the Nether faster.
Nether Portal CalculatorConvert Minecraft Overworld coordinates to Nether coordinates and back, so your portals link to the right place every time→
Spotting one
Look for a portal frame with netherrack and 
Magma block patches around it. They show up in the Overworld (except the deep dark) and all over the Nether.
The chest
Ruined portals usually have a loot chest nearby. It can contain:
- Gold tools, armour and ingots
- Obsidian and flint and steel
- A
Lodestone on newer versions
Some portals also have a Block of gold built in.
Gold for piglinsWear a gold armour piece from the chest before going to the Nether so piglins don't attack you.
Fixing the portal
- Count the missing obsidian in the frame.
- Swap any crying obsidian for regular obsidian. Crying obsidian won't let the portal light.
- Fill the gaps, then light it with flint and steel.
Need a diamond pickaxeTo move obsidian you need a diamond or netherite pickaxe. Without one, use water and lava to make new obsidian in place.
Cheat sheet
- Look for netherrack and magma around a frame
- Chest with gold, obsidian and flint and steel
- Crying obsidian blocks the portal
Waypoint ManagerSave Minecraft waypoints across your worlds→
How Nether Portal Linking Works
Why Your Anvil Says Too Expensive
Shulker Box Storage Maths