Amethyst Geodes is a natural structure added to Minecraft 1.17. You should know that they are only available in the Overworld at levels between 1 and 64.
These blocks appear to be a smooth outer layer of Basalt. Basalt is sometimes mistaken for Obsidian by some players. Make sure you look closely when you encounter dark-colored blocks during mining. Rarely, you might find them with cracks, which allows players to see the inside of the purple and white blocks. You can find them underwater, or even in caves. No matter where it is located, an Amethyst Geode can be found if there is a large, curved structure that has a Basalt outer layer.
You can get the Amethyst Shards into the geode by simply breaking into it with a Stone Pickaxe. After you have broken through the Basalt layer, you will find Calcite. To find Amethyst Shards, you must break through this layer!