Rn,
Blackrock is the ingredient use to cast the Armageddon spell
Vas Kal An Mani In Corp Hur Tym.
I think it's only on the FoF because it's dropping as one of the Treasure of Tokuno but currently it has no use whatsoever. They probably forgot to code it out...
Players are basically asking what's up with the Blackrock dropping as a ToT when it's pretty junk/worthless. That's why I think it appeared on the FoF. Players don't want to spend their time farming for ToT's to get a piece of junk. Would you rather have a Mempo or a piece of Blackrock that can easily be obtained mining?
Who knows just how much blackrock is out there that has been mined over the years. You can put it on the ground and it doesn't decay so that only compounds the problem. It would be absolute overkill the Dev's ever allowed Blackrock to be turned in for any type of reward. Think of how much all the script miners have....
I have a ton and I spent very little time mining.
We get the same old response from the Dev's when we ask about what purpose of Blackrock "It will have a use soon!"...
But as of right now it has NO USE whatsoever.
Here is what UOGUIDE has on the History & Lore of BR if your interested
Look Here