The age old mystery of the Glowing Black Stone is finally solved...
"Looks like the Glowing Black Stone is the item required to complete the quest described as "APPQuestJohnC"
The "APP" prefix means it was created by a design apprentice who was tinkering with the tools and learning the game. This isn't a quest that can actually be completed. Years later, when QUEST flags were applied to items APPQuestJohnC was picked up in the query and the GBS was flagged as a quest item. I don't know who JohnC is. The quest was created on 2/26/2000 so this predates me by over 2 years.
Hope this helps solve the mystery!
-Prathun"