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:

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

  • transaction id;
  • transaction output index;
  • transaction output value (amount of coins burnt);
  • script as hexadecimal string;
  • decoded script.