Minecraft: Java Edition Snapshot 21w11a tweaks copper and lightning rods from 'Caves and Cliffs Update'

Minecraft Caves and Cliffs Update Image (Image credit: Mojang Studios)

What you need to know

Minecraft: Java Edition tests future updates and changes through update "slices" called snapshots.
Recent snapshots have all been testing features from the upcoming 'Caves and Cliffs Update.'
The latest one, Snapshot 21w11a, makes some changes to copper, waxing, and oxidization.
There's also the usual suite of general improvements and bug fixes in this snapshot.

Minecraft: Java Edition continues to push forward on the Caves and Cliffs Update with the release of Snapshot 21w11a. Today's Minecraft snapshot focuses mostly on copper, the newest ore being added to Minecraft. Changes are being made to how players wax or un-wax copper, the way lightning rods work, and more. For example, lightning striking lightning rods now reverses oxidization on surrounding copper blocks.

Players who participate in Minecraft: Java Edition snapshots will also notice a lot of other smaller improvements, especially to the recently introduced lush cave biome.

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The full changelog for Minecraft: Java Edition Snapshot 21w11a includes:

New features

Lightning rods can now, for the very first time ever, be waterlogged
New functionality for applying and removing wax from Copper
Bonemealing rooted dirt now grows hanging roots underneath

Waxing copper & oxidization

Right-click with Honeycomb on Copper Blocks to wax them
Use honeycomb in a dispenser to wax Copper Blocks
Axes can scrape off wax and oxidation of Copper Blocks
Lightning strike hitting Copper will clean its oxidation

Changes

Waxed Copper Blocks can be crafted into 4 Copper Ingots
Tweaked the cave sizes
Slightly increased the frequency of Diamond Ore blobs
Hanging roots block now renders randomly offset
Breaking a Big Dripleaf stem now drops a Big Dripleaf Block
Moss Blocks can be crafted with cobblestone or stone bricks to make the mossy versions of those blocks
The facing direction of Small Dripleaf Blocks is now determined by which direction the player is facing when placing it
Fully-grown Amethyst Clusters now drop 4 Amethyst Shards (or more with Fortune) when mined with a pickaxe, and drop 2 Amethyst Shards when broken by hand, piston, or other means

Technical changes

Added F3 + L shortcut to generate and persist performance metrics from in-game

In-game client metrics reporting

Pressing F3 + L while in the game will start a recording for 10 seconds capturing metrics such as tick durations, used heap sizes, and other more detailed stats. These will be saved to a zip file in debug/profiling/<yyyy-MM-dd_HH.mm.ss>.zip and could be used for performance regression analysis if included in bug reports
The exact metrics, output format, and names are susceptible to change between versions, and our plan is to continue iterating on which metrics to capture

Bug fixes

Snow covered grass / podzol / mycelium block side texture does not match original block
Lava / water / powder snow bucket desync when using it while rapidly turning
False negatives during occlusion culling
Spectators can't see through lava
Librarian and zombie librarian torso top texture is incorrect
Spectral arrow texture on item and entity aren't consistent
Brewing Stand bottle outline incorrect
Overworld wood signs use the outdated wood texture on all sides
Jungle door inventory texture is outdated
Painting back texture has not been updated with the texture update
Smoker's top and bottom textures have inconsistently colored pixels
Carved pumpkins and jack o'lanterns create swastikas
Jigsaw Structures causing DataFixer spam
Floating pixel in the tailfin of a guardian / elder guardian
Area effect cloud does not enforce a maximum radius
block.amethyst_block.chime has no subtitle
Amethyst crystal cluster drops items when block is moved directly by a piston without actually breaking the block
Inconsistency: Breaking amethyst crystals with hands doesn't drop the item, but breaking the block they are placed on drops them
Tinted Glass suffocates entities inside of it
Spyglass use statistic never increases
Mobs can spawn on tinted glass
When filling a lava cauldron with lava, the lava is placed on the ground, not in the cauldron. This also affects powder snow
Tinted glass is not included in the impermeable tag
Lightning rod can spawn skeleton horses with skeletons
World Border is rendered upside down
Frozen hearts in hardcore mode look identical to frozen hearts in survival mode
Trident returning to owner not in the same world can cause permanent player kick
Player lighting is inconsistent in the inventory and appears darker on the front
Bone Meal can still be used on a Glow Lichen when it is unable to grow
Cannot compost glow lichen
Spectators can't see through powder snow
Removing the block supporting a spore blossom allows the spore blossom to float
Cave vine blocks are inconsistent in ID from other similar blocks
Removing the support block for hanging roots allows it to float
Cave vines cannot be climbed
Cave vines do not slow you down like other vines
Cave vines head and body emit different light levels
Bone meal cannot be used on dripleaf stems
Cave vines body and cave vines head share the same name
Moss appropriate tool is axe rather than hoe
Setting a lectern on fire causes z-fighting
Snow layers in "Snowy Kingdom" superflat preset generate 64 blocks above the ground
Azaleas cannot be used as a fuel
Gilded blackstone texture does not match the new side texture of blackstone
Player takes no fall damage on blocks above y=316
Sugar cane item texture is no longer accurate from 13w36a forward
When replacing tuff, ores still generate with a "stone" background below y=0
Teams become dysfunctional when any entity leaves the team
Flat "slices" of terrain generating in cracks
Potential optimization target in DepthBasedReplacingBaseStoneSource
stat.fallOneCm is not updated when falling onto a block above y=316
Some blocks generate at wrong Y height in a superflat world
Lightning rod still can't be waterlogged
Debug chunk borders don't render properly
Debug pie is blacked out
Water has no fog anymore
Screen turns dark grey when switching dimension
Hanging roots can generate hanging on other hanging roots, making them float
Mipmapping causes some block faces to become too dark
Banners are unimpacted by light levels
Cannot enchant items
With fast graphics, the freezing overlay renders black, and covers the whole screen black in first person
Broken spyglass overlay on fast graphics
Red vignette shown when outside the world border is too intense
The carved pumpkin overlay turns the screen completely black when using fast graphics
The green nausea overlay no longer renders
Glowing effect no longer changes to team color
Floating water generates excessively in lush caves
The nether portal overlay no longer renders, whilst using fast graphics
Shulkers do not flash red when hurt or killed
Debug pie has purple box when moving an enchanted item
Right clicking to open alternate recipes does not show the recipes
Noise cave entrances cause unnatural, smooth edges in terrain
Caves generate with very blocky areas
At sunset, a blue line appears in the northern and southern skies
Ambient occlusion of the player seen in the survival inventory has changed
Glowing effect no longer renders around translucent pixels
Two white lines appear on the Mojang loading screen
Cave Vines can generate without supporting blocks
M1 ARM Macs crash when using Fabulous Graphics mode as was the case in older versions, but no lack of support warning is shown
World border is white
You can see block hitboxes very clearly whilst in powder snow/lava
Mojang logo screen flashes blue before changing to red
World border is occasionally shown as a solid color upon being loaded
The red flash when a mob is hurt / killed appears to be slightly dimmed
When selecting text in the end, the sky gets highlighted
The background of hover-event text becomes blue when text is selected in an anvil or chat
Spyglass has a gradient effect while freezing
Cave ceilings and floors sometimes too flat or blocky
Fire is rendered dark in the player / horse / llama UI
Transparency buffers start with blue background instead of empty background
The wither's wither armor has a blue aura around it
The background opacity of subtitles and chat, are affected by a potion effect UI fading out
Charged creeper layer makes clouds and entities invisible
World border is shown as a solid color when picking up items or experience orbs
World border does not render when below the world
Reloading resource packs no longer shows the progress bar while the transparent background is shown
Entity hitboxes can be seen whilst inside of powder snow/lava
Chat scroll bar is offset
Social interactions scroll bar appears broken
Xray with spyglass
Cast fishing line is disconnected from the rod
Slime blocks, honey blocks, stained glass, and ice are fully lit when moved by pistons
Xray using enchanted items
Entity shadows can be seen whilst inside of powder snow/lava
The background opacity of command syntax help is affected when highlighting text
Being inside of a block no longer shows the block texture
Dying ender dragon is rendered too bright
Lead / fishing line is no longer affected by the fog from powder snow/lava
End portal and end gateway textures expand as the player travels further from the block