Black Rare Sat 20,159,999,999,999

Black Sats are the second most popular rare Sats category, only after the Uncommons Sats. They are widely adopted by the Ordinals community in general, and their total supply is exactly the same as Uncommon Sats. Just as Uncommon Sats, their rarity is related to the position of the Satoshis inside the blockchain, and this makes its rarity properties much less subjective and much more clear then the other Sats categories, which is one of the main reasons for their value accrual and adoption.

Black Sats are the Satoshis that come right before each block - in contrast to Uncommon Sats, which are the first Satoshi of every block. Black Rare Sats on the other hand are the Satoshis that come right before a difficulty adjustment period - in contrast to Rare Sats, which are the first Satoshi of every difficulty adjustment period. Difficulty adjustments happen once every 2016 blocks, and each block happens every 10 minutes. Which means that a new Black Rare and Rare Sats are created every 20160 minutes on average (approximately once every 14 days).

Most Satoshis from the first blocks of 2009 haven't moved since they were mined. Satoshi Nakamoto (or some other Bitcoin early adopter) has mined them and stored them in a Bitcoin address, and they remain in this same address until today. These kinds of Sats are considered to be inaccessible by the Sat collectors, since the only way to get them would be if said miner would go to their 2009 wallet and spend them.

As said previously, Rares and Black Rares are a reference to a Satoshi's position in the blockchain, comparing their distance to the Bitcoin mining difficulty adjustments. Since difficulty adjustments happen once every 2016 blocks, the first difficulty adjustment happened on 2009-01-27, on block 2016. The first Sat from block 2016 is the first Rare Sat ever created, and the last Sat from block 2015 is the first Black Rare. Both these Sats are still in the same wallet that have mined them and are unattainable. 

Links for verification:

https://mempool.space/block/2016

https://mempool.space/block/2015

The second difficulty adjustment happened on ‎2009-02-12, on block 4032. The first Sat from block 4032 is the second Rare Sat ever created and the last Sat from block 4031 is the second Black Rare. The Rare Sat from block 4032 has never moved since it was mined and is unattainable. 

Link for verification:

https://mempool.space/block/4032

The Black Rare from block 4031 is currently on offer. It was mined on 2009-02-12, and the miner has sent those Bitcoin to another address on 2011-11-17, more than 2 and a half years later.

These Bitcoin's activity since the day they were mined can be traced using this link: https://mempool.space/block/4031

This is the oldest Rare Sat that can be attained, including both Rares and Black Rares.