Add to en_us.json

"block.tutorialmod.amethyst_ore": "Amethyst Ore",

Add to TutorialMod Constructor.java

ModBlocks.register(eventBus);

blockstates-amethyst_ore.json

{
    "variants": {
        "": { "model": "tutorialmod:block/amethyst_ore" }
    }
}

loot_tables-amethyst_ore.json

{
  "type": "minecraft:block",
  "pools": [
    {
      "rolls": 1,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "tutorialmod:amethyst"
        }
      ]
    }
  ]
}

ModBlocks.java

public class ModBlocks {

    public static final DeferredRegister<Block> BLOCKS
            = DeferredRegister.create(ForgeRegistries.BLOCKS, TutorialMod.MOD_ID);

    public static final RegistryObject<Block> AMETHYST_ORE = registerBlock("amethyst_ore",
            () -> new Block(AbstractBlock.Properties.create(Material.ROCK)
                    .harvestLevel(2).setRequiresTool().harvestTool(ToolType.PICKAXE).hardnessAndResistance(5f)));


    private static <T extends Block>RegistryObject<T> registerBlock(String name, Supplier<T> block) {
        RegistryObject<T> toReturn = BLOCKS.register(name, block);
        registerBlockItem(name, toReturn);
        return toReturn;
    }

    private static <T extends Block> void registerBlockItem(String name, RegistryObject<T> block) {
        ModItems.ITEMS.register(name, () -> new BlockItem(block.get(),
                new Item.Properties().group(ModItemGroup.TUTORIAL_GROUP)));
    }

    public static void register(IEventBus eventBus) {
        BLOCKS.register(eventBus);
    }
}

models-block-amethyst_ore.json

{
  "parent": "block/cube_all",
  "textures": {
    "all": "tutorialmod:block/amethyst_ore"
  }
}

models-item-amethyst_ore.json

{
  "parent": "tutorialmod:block/amethyst_ore"
}