Crystal Block! Add a Custom Glowing Block to Minecraft

1

🧱

How Blocks Work in Fabric

Understand the difference between items and blocks before we write any code

Active

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Goal for this step

Understand what extra files a block needs compared to an item, so nothing surprises you later.

📖

Blocks vs Items: In Minecraft, a Block is what sits in the world. A BlockItem is the item version you hold and place. Every block needs both registered. Blocks also need a blockstate JSON (describing which model to show) and a loot table (what drops when mined).

Files we'll create this episode

1ModBlocks.java registers the Crystal Block (and its BlockItem)
2models/block/crystal_block.json the 3D cube model
3models/item/crystal_block.json the item version model
4blockstates/crystal_block.json links state → model
5textures/block/crystal_block.png the 16×16 texture
6loot_table/blocks/crystal_block.json what drops when mined
7recipe/crystal_block.json crafting recipe

💡

That's more files than an item! But each one is small and follows the same pattern. Once you've done it once, you can add any block in minutes.

I understand blocks need both a Block and a BlockItem registered

I know blocks need a blockstate, model, texture, and loot table

2

📝

Create ModBlocks.java

Register the Crystal Block and its BlockItem in Java

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Goal for this step

Create ModBlocks.java with the Crystal Block registered as a glowing, mineable block.

1Open your CrystalMod project in IntelliJ. Right-click the crystalmod package → New → Java Class. Name it ModBlocks.
2Replace the file contents with:

ModBlocks.java

package com.example.crystalmod;

import net.fabricmc.fabric.api.itemgroup.v1.ItemGroupEvents;
import net.minecraft.block.AbstractBlock;
import net.minecraft.block.Block;
import net.minecraft.block.MapColor;
import net.minecraft.item.BlockItem;
import net.minecraft.item.Item;
import net.minecraft.item.ItemGroups;
import net.minecraft.registry.Registries;
import net.minecraft.registry.Registry;
import net.minecraft.sound.BlockSoundGroup;
import net.minecraft.util.Identifier;

public class ModBlocks {

    public static final Block CRYSTAL_BLOCK = registerBlock(
        "crystal_block",
        new Block(AbstractBlock.Settings.create()
            .mapColor(MapColor.CYAN)
            .strength(3.0f, 4.0f)        // hardness, blast resistance
            .luminance(state -> 10)         // glow level (0-15)
            .requiresTool()                  // needs pickaxe to drop
            .sounds(BlockSoundGroup.AMETHYST_BLOCK))
    );

    private static Block registerBlock(String name, Block block) {
        registerBlockItem(name, block);
        return Registry.register(Registries.BLOCK,
            Identifier.of(CrystalMod.MOD_ID, name), block);
    }

    private static Item registerBlockItem(String name, Block block) {
        return Registry.register(Registries.ITEM,
            Identifier.of(CrystalMod.MOD_ID, name),
            new BlockItem(block, new Item.Settings()));
    }

    public static void registerModBlocks() {
        ItemGroupEvents.modifyEntriesEvent(ItemGroups.BUILDING_BLOCKS)
            .register(entries -> entries.add(CRYSTAL_BLOCK));
    }
}

📖

luminance(state -> 10) makes the block glow with brightness 10 (like a glowstone is 15, torch is 14). requiresTool() means it only drops when mined with the correct tool (pickaxe).

ModBlocks.java created with CRYSTAL_BLOCK field

No red import errors (use Alt+Enter to fix if needed)

3

🔗

Register ModBlocks in CrystalMod.java

Call your new registerModBlocks() method so the block loads on startup

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Goal for this step

Add one line to CrystalMod.java so your block gets registered when the game starts.

1Open CrystalMod.java.
2In the onInitialize() method, add a call to ModBlocks.registerModBlocks(); put it before the ModItems line:

CrystalMod.java onInitialize()

@Override
public void onInitialize() {
    ModBlocks.registerModBlocks();  // ← add this line
    ModItems.registerModItems();
    LOGGER.info("Crystal Mod loaded! 💎");
}

💡

Blocks must be registered before items because the BlockItem references the Block object. Registering blocks first avoids any ordering issues.

ModBlocks.registerModBlocks() added to onInitialize()

🎓 Teacher Note Step 3Students commonly forget that blocks need a BlockItem too — a block without a BlockItem exists in the world but can't be picked up or placed from inventory. Also watch for the registration order: blocks must be registered before items because BlockItem holds a reference to the Block object.

🚨 Stuck? Block won't register or game crashes

Cannot find symbol: ModBlocks check ModBlocks.java is in the com.example.crystalmod package and the package declaration at the top of the file matches.
Block not in creative inventory confirm registerModBlocks() adds the block via ItemGroupEvents with entries.add(CRYSTAL_BLOCK).
Game crashes on startup make sure ModBlocks.registerModBlocks() is called before ModItems.registerModItems() in CrystalMod.java.
Block is invisible when placed the blockstate or model JSON is missing or named wrong. Check Step 6.

4

🎨

Create the Block Texture

Draw a 16×16 crystal texture for your block's six faces

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Goal for this step

Create a PNG texture for the Crystal Block and save it in the right folder.

1In your project's resources/assets/crystalmod folder, create a new subfolder: textures/block.
2Use Pixel Studio or any image editor to draw a 16×16 crystal texture. Try cyan/teal shades with lighter spots for a crystal-like appearance.
3Save it as crystal_block.png in the textures/block/ folder.

🎨

Look at Minecraft's amethyst block or glass textures for inspiration simple semi-transparent looking patterns with lighter edges work really well for crystals!

crystal_block.png created at assets/crystalmod/textures/block/

5

📦

Create Block & Item Model JSON Files

Tell Minecraft which texture to use and what shape the block is

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Goal for this step

Create two JSON model files one for the block in the world, one for it as a held/placed item.

Block model (the 3D cube)

1In assets/crystalmod, create the folder models/block.
2Create the file crystal_block.json inside it:

assets/crystalmod/models/block/crystal_block.json

{
  "parent": "block/cube_all",
  "textures": {
    "all": "crystalmod:block/crystal_block"
  }
}

Item model (what you hold)

3In assets/crystalmod/models/item (which you created in Episode 1), create crystal_block.json:

assets/crystalmod/models/item/crystal_block.json

{
  "parent": "crystalmod:block/crystal_block"
}

📖

The item model just points to the block model — Minecraft knows how to render a block model as an item automatically. Nice and simple!

models/block/crystal_block.json created

models/item/crystal_block.json created

6

🔀

Create the Blockstate JSON

Link the block's state to its model required for every block

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Goal for this step

Create the blockstates JSON this tells Minecraft which model to use for the block's default state.

1In assets/crystalmod, create the folder blockstates.
2Inside it create the file crystal_block.json:

assets/crystalmod/blockstates/crystal_block.json

{
  "variants": {
    "": { "model": "crystalmod:block/crystal_block" }
  }
}

📖

Some blocks have many variants (like stairs or slabs that can face different directions). Our Crystal Block only has one variant the empty string "" means "default state".

3Add the block's name to your en_us.json language file:
"block.crystalmod.crystal_block": "Crystal Block"

blockstates/crystal_block.json created

en_us.json updated with block name

🎓 Teacher Note Step 6A pink/magenta checkerboard block means a missing texture or wrong path. Ask students to open the Gradle run console and search for "crystalmod" any missing resource errors are listed there. Common path mistake: "textures/blocks/" (with an s) instead of the correct "textures/block/".

🚨 Stuck? Block shows as pink/black checkerboard

Pink checkerboard = missing texture. The PNG must be at assets/crystalmod/textures/block/crystal_block.png folder is block, not blocks.
Blockstate not found the JSON must be at assets/crystalmod/blockstates/crystal_block.json folder is blockstates (with an s, unlike texture).
JSON syntax error a missing comma or bracket breaks the whole file. Paste your JSON at jsonlint.com to check.
Block model not found block model goes in models/block/ and the item model goes in models/item/. Two separate files in two separate folders!

7

💰

Add a Loot Table Drop Crystal Gem When Mined

Tell Minecraft what items to drop when the Crystal Block is broken

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Goal for this step

Create a loot table so that mining the Crystal Block drops 1 Crystal Gem.

1In src/main/resources, navigate to the data folder. Create the path: data/crystalmod/loot_table/blocks/
2Create the file crystal_block.json inside it:

data/crystalmod/loot_table/blocks/crystal_block.json

{
  "type": "minecraft:block",
  "pools": [
    {
      "rolls": 1,
      "bonus_rolls": 0,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "crystalmod:crystal_gem"
        }
      ],
      "conditions": [
        {
          "condition": "minecraft:survives_explosion"
        }
      ]
    }
  ]
}

📖

rolls: 1 means drop 1 item. survives_explosion means creepers won't drop the gem (realistic behaviour blow up a block and you lose the loot!). Remove that condition if you want it to always drop.

loot_table/blocks/crystal_block.json created

8

🔨

Add a Crafting Recipe

Let players craft the Crystal Block using 9 Crystal Gems in a 3×3 grid

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Goal for this step

Create a crafting recipe so players can turn 9 Crystal Gems into 1 Crystal Block (like iron ingots → iron block).

1In data/crystalmod, create a recipe folder.
2Create the file crystal_block.json inside it:

data/crystalmod/recipe/crystal_block.json

{
  "type": "minecraft:crafting_shaped",
  "pattern": [
    "GGG",
    "GGG",
    "GGG"
  ],
  "key": {
    "G": { "item": "crystalmod:crystal_gem" }
  },
  "result": {
    "id": "crystalmod:crystal_block",
    "count": 1
  }
}

💡

Want a different recipe? Change the pattern! "G G" with spaces means the middle column is empty. You could make a 2×2 recipe using just 4 gems by using only the top-left 2×2 area of the pattern.

data/crystalmod/recipe/crystal_block.json created

9

🏃

Run Minecraft & Test Your Block!

Launch the game and place your glowing Crystal Block in the world

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Goal for this step

Launch Minecraft, find your Crystal Block in creative mode, place it and see it glow!

1In IntelliJ, select Minecraft Client from the run dropdown and click ▶ Play.
2Create or open a creative world.
3Press E → search for Crystal Block. It should appear in the Building Blocks tab.
4Place it in the world. It should look like your texture and glow in the dark!
5Switch to Survival mode (/gamemode survival) and try to mine it you'll need a pickaxe, and it should drop a Crystal Gem when broken.
6Test the crafting recipe: open a crafting table and fill all 9 slots with Crystal Gems you should get 1 Crystal Block.

⚠️

If the block appears purple/black (missing texture) check the texture file is exactly named crystal_block.png and is in the right folder. Check the blockstates JSON matches that name too.

Crystal Block appears in creative inventory

Block glows in the dark when placed

Mining with a pickaxe drops a Crystal Gem

Crafting recipe works in a crafting table

10

🌟

Challenge: Tweak Your Block's Properties

Experiment with hardness, glow level, sounds and map colour

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Goal for this step

Customise your Crystal Block's properties to make it exactly the way you want it.

🎨

Try changing these values in your block settings and see what happens:

1Glow: Change luminance(state -> 10) to 15 for maximum brightness, or 4 for a subtle glow.
2Hardness: Change strength(3.0f, 4.0f) to strength(50.0f, 1200.0f) to make it as hard as obsidian!
3Sound: Try BlockSoundGroup.GLASS, BlockSoundGroup.METAL or BlockSoundGroup.STONE each gives a different sound when walked on and mined.
4Map colour: Try MapColor.BLUE, MapColor.PURPLE or MapColor.EMERALD_GREEN this changes the colour the block shows on a map.
5Reload Minecraft after each change to see it work.

I tried at least one property change and saw it work

Crystal Block!Your First Custom Block

Files we'll create this episode

Block model (the 3D cube)

Item model (what you hold)

Crystal Block!
Your First Custom Block