{
    "variants": {
        "variation=tiny": { "model": "rocks:block/tiny_netherrack_rock" },
        "variation=small": { "model": "rocks:block/small_netherrack_rock" },
        "variation=medium": { "model": "rocks:block/medium_netherrack_rock" },
        "variation=large": { "model": "rocks:block/large_netherrack_rock" }
    }
}