Unknown miners.

“Unknown” is the label mempool.space gives a block it can’t tie to any mining poolMining poolA group of miners who share the work of finding blocks and split the rewards, so each gets paid steadily instead of rarely.. It isn’t a pool, a company or one miner, and it doesn’t mean anything is wrong: an Unknown block confirms the transactions inside it like any other block. Pools usually write their name into a block’s first transaction, which pays out the block’s reward, and some pay that reward to addresses known to be theirs. mempool.space checks every block against a public list of pools’ names and addresses, and a block that matches neither is Unknown. Writing a name is up to the miner; no rule of Bitcoin requires it.

Every block before 14 June 2011, more than 130,000 of them, is Unknown. Bitcoin’s original software wrote no name into the blocks it mined, and the first public mining pools, which opened at the end of 2010, didn’t name theirs either: block 97,834, the first found by slush’s pool, on 16 December 2010, is Unknown. The first block mempool.space ties to a pool is Eligius’s block 130,635. Most blocks of 2011 and 2012 are Unknown too, but since 2015 Unknown blocks have been fewer than 6% of each year’s, and since 2022 fewer than 1%.

The researcher Sergio Demian Lerner believes that many of the earliest Unknown blocks came from a single miner. In 2013 he found a pattern in the early blocks that he says marks its work, and he later called the miner “Patoshi”. By his count it found about 22,000 blocks, from block 1 in January 2009 until about May 2010, earning about 1.1 million bitcoin, and when he wrote in 2019 the rewards of 99.9% of those blocks had never been spent. He links Patoshi to Satoshi Nakamoto, Bitcoin’s creator, but says the link rests on “unsigned emails and not math”, so “we’ll never be sure”.

Some pools and individual miners still leave their name out of their blocks or write something generic, and a pool that starts using a new name can show as Unknown until mempool.space adds it to its list. When the list changes, older blocks that match get the pool’s name: two blocks NiceHash found on 13 January 2026 under a new tag, “NiceHashMining”, were Unknown until mempool.space added the tag on 16 January, and now show NiceHash.