Java Edition 20w45a

20w45a is the first snapshot for Java Edition 1.17, released on November 4, 2020, which adds the first Caves & Cliffs features.

Blocks

 * Amethyst Bud
 * Grows from budding amethyst, which is found in amethyst geodes.
 * Starts out small, but grows into medium after a while, large after even more time and eventually becomes an amethyst cluster.
 * Unlike crops, each growth stage is a separate block instead of a block state.
 * Drops nothing if broken, even with Silk Touch.


 * Amethyst Cluster
 * The final stage of the amethyst bud, which grows from budding amethyst in amethyst geodes.
 * Drops amethyst shards if broken, in an amount affected by Fortune, but can also be picked up with Silk Touch.
 * Emits a light level of 5.


 * Block of Amethyst
 * A block found in amethyst geodes.
 * Unlike the Budding Amethyst, the Block of Amethyst can be obtained when mined.
 * Can also be crafted with 4 amethyst shards.


 * Budding Amethyst
 * Generates amethyst crystals on any of its sides (if next to a water source block or air, and if the side is not against another block), in a given time.
 * Cannot be obtained when mined, even with Silk Touch, and will not drop anything.
 * Will break immediately if pushed by a piston or sticky piston.
 * Cannot be pulled by sticky pistons.
 * Generates in amethyst geodes.


 * Calcite
 * An off-white stone that generates in amethyst geodes, between tuff and the actual amethyst.


 * Candle
 * Crafted with honeycomb and string.
 * Comes with 16 dyed types and a non-dyed type.
 * Can be lit by any item that produces fire.
 * Up to 4 can be placed in a single block, similar to sea pickles, for a maximum light level of 12.
 * Only similarly-colored candles can be placed on the same block.
 * Only one can be placed on uneaten cake and lit.
 * If any of the cake is consumed the candle pops off.
 * Can be placed, but cannot be lit, underwater.


 * Copper Block
 * Can be crafted with 9 copper ingots, and can also be crafted back into 9 copper ingots.
 * Oxidises and changes texture over time.
 * Can be stopped from oxidising by combining it with a honeycomb to create a Waxed Copper Block.
 * Can be crafted into cut copper.


 * Copper Ore
 * Generates randomly underground in small veins, but this has been confirmed to be a placeholder.
 * Has the same rarity as iron and coal.
 * Generating starts at the same minimum level(s) as iron and coal.
 * Can be smelted into a copper ingot.


 * Cut Copper
 * Can be made into stair and slab variants.
 * Oxidises and changes texture over time.
 * Can be stopped from oxidising by combining it with a honeycomb to create Waxed Cut Copper.


 * Cut Copper Slab
 * Oxidises and changes texture over time.
 * Can be stopped from oxidising by combining it with a honeycomb to create a Waxed Cut Copper Slab.


 * Cut Copper Stairs
 * Oxidises and changes texture over time.
 * Can be stopped from oxidising by combining it with a honeycomb to create Waxed Cut Copper Stairs.


 * Lightning Rod
 * Can be crafted with 3 copper ingots.
 * Nearby lightning strikes within a 16 block radius will be redirected to the lightning rod.
 * Gives off a redstone signal with a strength of 15 if hit by lightning.
 * Can be activated directly by throwing a channeling trident at it during a thunderstorm, though this does not produce a redstone signal.


 * Tinted Glass
 * A variant of glass that does not let light pass through.
 * Can be crafted with 4 amethyst shards and a glass block.
 * Stained glass cannot be used to craft tinted glass.
 * Will drop itself if mined without Silk Touch, unlike glass.


 * Tuff
 * A grayish stone that composes the outer layer of amethyst geodes.

Items

 * Amethyst Shard
 * Obtained from breaking amethyst clusters.
 * The amount dropped can be increased with the Fortune enchantment.
 * Can be used to craft tinted glass, blocks of amethyst and a spyglass.


 * Bundle
 * Can be crafted with string and rabbit hide.
 * Used to store other items inside of it.
 * Can only hold a stack of items, but is able to hold different types of items inside of it.
 * Items with smaller stacks, such as ender pearls, take up more room in a bundle.
 * Non-stackable items take up the whole space.
 * The bundle's contents can be opened by pressing right-click while holding it.
 * Cannot hold shulker boxes.
 * Even though bundles are not stackable, bundles can be nested.
 * Can hold up to 16 bundles.
 * Only empty bundles can be placed in other bundles without using commands.
 * Note: Bundles can hold any amount of any item if added using commands.


 * Copper Ingot
 * Obtained by smelting copper ore. Does not drop from the ore itself.
 * Used to craft copper blocks, lightning rods and spyglasses.


 * Spyglass
 * Crafted with 2 copper ingots and a amethyst shard.
 * When used, zooms in on wherever the player is looking, but limits their view to a small circle.
 * The overlay that limits the view can be removed with a resource pack or by pressing.
 * There is a unique animation for using the spyglass, which is visible in third person perspective.

World generation

 * Amethyst Geodes
 * A new feature found uncommonly underground (can rarely appear exposed to the surface close to sea level).
 * Contains blocks of amethyst and budding amethyst blocks, which are encased in a shell of calcite and tuff.
 * Also generates with a small air pocket nearby which may open into the geode.
 * Generally generates at or below sea level (y = 63).
 * Most commonly generates at lower levels (y = 0 to y = 40)
 * Overrides standard caves and ravines, but is overridden by abandoned mineshafts.

General

 * Loot tables
 * New functions:
 * Sets tags needed for banner patterns. Parameters:
 * patterns - list of pattern objects:
 * pattern - name of pattern (square_bottom_left, bricks, etc.)
 * color - name of color (light_gray, etc.)
 * append - if true, new elements will be appended to existing ones instead of replacing


 * Tags
 * Added the block tag.
 * Contains all 17 types of candle cake.
 * If the player puts a candle on a cake, and keeps clicking the candle on the cake, the candle will be duplicated.
 * Blocks in this tag are considered candle cakes and can be lit, if they have the block states set to false.
 * Added the block and item tags.
 * Contains all 17 types of candles.
 * Blocks in this tag are considered candles and can be lit, if they have the block states and both are false.
 * Cakes use this tag to determine if a candle item can be placed on it or not.
 * Added the block tag.
 * Contains cauldrons, water cauldrons, and lava cauldrons.
 * This tag is used in certain pathfinding processes.
 * Added the block tag.
 * Contains amethyst blocks and budding amethyst.
 * Blocks in this tag play play the "amethyst block chime" sound repeatedly for a short amount of time after being stepped on, gradually decreasing in volume.
 * Added the item tag.
 * Contains leather.
 * Baby piglins do not attempt to pick up items in this tag. Adult piglins are unaffected. Baby piglins still follow the other rules adult piglins follow.
 * If an item is in this tag while simultaneously being recognized as a wanted item by piglins, this tag takes precedence.
 * Added the item tag.
 * Contains raw and cooked porkchop.
 * Piglins can eat items in this tag.
 * Eating refers to the piglin seeking out and picking up an item without appearing in its inventory, thus vanishing.

Blocks

 * Cauldrons
 * Can now be filled with lava.
 * Lava filled cauldrons give off a redstone comparator signal of strength 1.
 * Have been split into normal, water and lava cauldrons.
 * Grass Path
 * Renamed to "Dirt Path," as per Bedrock Edition.
 * The block id has also been updated to.
 * Can now be made on top of dirt, coarse dirt, mycelium, and podzol.
 * Pistons
 * Particles now appear if a block is broken by a piston.
 * Breaks Budding Amethyst if pushed/pulled w/ a piston/sticky piston.


 * Rails
 * Are now able to be waterlogged.
 * No longer break when contacted by water.
 * Water
 * Flowing water no longer breaks rails.

Items

 * Firework Rockets
 * Simple firework rockets with one gunpowder can now be crafted using the recipe book.

Mobs

 * Shulkers
 * If a shulker is hit by another shulker's projectile, it now has a chance of spawning a new shulker. Shulkers are more likely to spawn new shulkers when there are fewer shulkers nearby.

Non-mob entities

 * Experience Orbs
 * Will now sometimes merge when in large quantities, to improve performance.
 * Merging will not affect the amount of experience gathered from collecting the merged orbs.
 * No longer follow dead players.


 * Minecarts
 * Can now move in water, but move considerably slower than they do on land.

General

 * Data and Resource Packs
 * Changed the  number in   from 6 to 7.
 * Split the  number into separate resource and data pack versions; the data pack version remains at 6.


 * Dedicated servers
 * A dedicated server can enforce custom resource packs by setting in . When this option is used, players will be prompted for a response and will be disconnected if they decline the required pack.


 * Entity storage
 * Entities have been extracted from main (terrain) chunks and are now stored in separate directory (similar to POI storage). Those new files are still region files with NBT.

Video
Video made by slicedlime: