Block of Copper

The block of copper is a decorative block that oxidizes over time, gaining a verdigris appearance. It can be crafted into a waxed version that does not oxidize. It can also be crafted back into four copper ingots unless it has started to oxidize, or been crafted into the cut variant.

Obtaining
Drowned can drop copper ingots, making copper blocks, slabs, stairs and lightning rods renewable resources.

Breaking
Blocks of copper can be mined only with a stone pickaxe or better. If a block of copper is mined without the use of a pickaxe, it drops nothing.

Waxing
Copper blocks can be turned into the respective waxed copper blocks by a honeycomb item on them.

Scraping
an axe on a waxed copper block turns it into the respective regular copper block. In addition, using an axe on an exposed, weathered, or oxidized copper block reverts it one stage to a regular, exposed, or weathered copper block respectively.

Usage
Blocks of copper can be used to store copper ingots in a compact fashion. Weathered, waxed, or cut variants cannot be crafted back into copper ingots. The cut variant can be crafted into slabs or stairs.

They have four stages of weathering (including the initial unweathered state). Advancing to the next stage of weathering relies on random ticks, and as such doesn't work in spawn chunks and other permanently loaded chunks, unless there is a player nearby.

Oxidation and Derusting
Copper blocks can oxidize over time, while lightning bolt and axe can remove rust layer on copper blocks.

Oxidation
The oxidation of copper blocks relies only on random ticks. Rain or water will not accelerate oxidation, and covering copper blocks with other blocks will not prevent oxidation.

$$, when a random tick is given, a copper block will have a $64/1125$ chance to enter a state called pre-oxidation. This probability makes a copper block enters pre-oxidation exactly every 20 minutes.

In pre-oxidation, the copper block will search its nearby unwaxed copper blocks for a distance of 4 blocks Manhattan distance. If there is any copper block that has a lower oxidation level, then the pre-oxidation ends, meaning that this copper block will not weather.

Let a be the number of all nearby unwaxed copper blocks, and b be the number of copper blocks that have a higher oxidation level. We derive the value of c from this equation: c = $b + 1/a + 1$. We also let the modifying factor m be 0.75 if the copper block has no oxidation level, or 1 if the copper block is exposed or weathered. Then the oxidation probability is mc2.

For example, a copper block surrounded by 6 copper blocks and 6 exposed copper blocks has a 21.7% chance to oxidize if it is given a random tick. In this case, a = 12 and b = 6.

Derusting
an axe on a waxed copper block turns it into the respective regular copper block. In addition, using an axe on an exposed, weathered, or oxidized copper block reverts it one stage to a regular, exposed, or weathered copper block respectively. Note that axe will be firstly applied on wax, then rust layers.

Lightning striking can also derust copper blocks.

When a lightning bolt strikes an unwaxed copper block(or the attached lightning rod), all rust layers of the block will be removed. The surrounded copper blocks are derusted according to an algorithm called random walk.

The position of the struck block will be set as start point. For each walk, a judgment point will be set at start point. For each step of the walk, the game randomly selects 10 blocks from a 3x3x3 area centered on the judgment point. If there is an unwaxed copper block in these 10 blocks, then the judgment point will transfer to that block, and remove 1 rust layer of the block. The length of a walk is between 1 and 8, and the amount of walks is between 3 and 5. This means that one single lightning strike can derust up to 41 blocks.

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