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 nine copper ingots unless it is in a fully or partly oxidized state or has been crafted into the cut variant.

Obtaining
Drowned can rarely 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.

Lightning strike
Unwaxed copper blocks are completely deoxidized when struck by lightning, and other unwaxed copper blocks nearby are deoxidized randomly.

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.

Oxidation
Copper blocks have four stages of weathering (including the initial unweathered state). They can oxidize over time, while lightning bolts and axes can remove the oxidation layer on copper blocks.

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

$$, when a random tick is given, a copper block has a $64/1125$ chance to enter a state called pre-oxidation. This means a copper block enters pre-oxidation after approximately 20 minutes.

In pre-oxidation, the copper block searches 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 does not weather.

Let a be the number of all nearby unwaxed copper blocks with same oxidation level, and b be the number of unwaxed all 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, an unweathered copper block surrounded by 6 unweathered copper blocks and 6 exposed copper blocks has a 21.7% chance to oxidize if it enters pre-oxidation state. In this case, a = 12, b = 6, and m = 0.75.

Deoxidation
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 the axe removes wax first, then oxidation layers.

Lightning can also remove oxidation from copper blocks. A lightning bolt striking an unwaxed copper block (or a lightning rod attached to one) removes all oxidation from the struck block, and may also deoxidize randomly selected copper blocks nearby. $$, these additional blocks are chosen by random walks as follows:
 * The position of the struck copper block is set as the start point. Then, the game performs 3 to 5 walks. In the beginning of each walk, a judgment point is set at the start point. For each step of the walk, the game randomly selects 10 blocks from a 3x3x3 volume centered on the judgment point. If an unwaxed copper block is found among these 10 blocks, the judgment point is transferred to the first such block found, and 1 oxidation layer of that block is removed (if the block is still unoxidized, the block stays as it is). The number of steps in a walk is between 1 and 8 (inclusive), chosen randomly for each walk. This means that one single lightning strike can deoxidize up to 41 blocks (1 block initially struck by lightning + 5 max walks*8 max steps in every walk).

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