Bitcoin-related cryptocurrencies contain the OP_RETURN opcode which can be used to create unspendable outputs, optionally containing some associated data. Usage of this opcode is generally not encouraged due to a threat of blockchain bloat, though if proper fee policy was introduced, it should do no harm. BlackCoin since version 1.2.3 contains a command named “burn” which creates such outputs.

I’ve written a simple Haskell application that inspects blockchain to find transaction outputs which use OP_RETURN . Using it, I’ve crawled BlackCoin’s blockchain from block 1 to 1697894. Some highlights:

There are 559 transaction outputs using OP_RETURN .

. There are 559 transactions containing outputs which use OP_RETURN .

. 91 transaction outputs have actually burnt some coins.

76 transaction outputs have burnt the minimum possible amount of coins, 0.00000001 BLK.

The largest amount of coins burnt is 2.4926 BLK.

Transaction d6409e30fcf96d60aae807f5d68468fba03b4accf1fb13c257969a24d2d3f5a9 contains text “Happy 3rd birthday!”.

Transaction 9ba558c64985d8452f4f65f47ea873d360e22e5697dcf6185125c4cbfaf4855b contains text “Big shout-out to janko33 for bringing Blackcoin to the 0.12 codebase |blackstat”.

Full results are available (paid in BLK), in the following format: