The Black Stone is an item that Robert E. Howard writes about in several of his short stories, including the modern day tale "The Black Stone", a pseudo-Conan the Barbarian story called "People of the Dark" and "Worms of the Earth", A Bran Mac Morn short.  The stories, especially the first, are all very evocative.  I've written down here some ideas for using the Black Stone in CoC.  A lot of this article is just synopses of the stories, which really speak for themselves. Currently, all three stories are in print in the book _Cthulhu : The Mythos and Kindred Horrors_ (Baen, 1987). 

A DESCRIPTION OF THE BLACK STONE

Howard speaks of two different black stones.  Though their locations are far removed, their descriptions seem very similar.  The black stone towers over a man, standing nearly sixteen feet tall.  It is octagonal in shape.  Across, it is approximately one and a half feet wide.  Strange symbols spiral around the column, from top to bottom. To an untrained eye, they might appear to be hieroglyphics, but in truth they are written in no script known to modern man.

The first of the two black stones is in the mountains of Hungary, near the small town of Stregoicavar.  The second of the black stones lies below the Earth, in a place called Dagon's Cave, somewhere in Britain. Whether the two stones might somehow be the same, or whether there might be more scattered across the world are unknown.

In "Worms of the Earth", a small black stone is described, an artifact of dwellers beneath the earth.  This stone too is carved with crytic letters, and it seems likely that it is a piece of one of the larger monoliths.


PURPOSE OF THE BLACK STONE

The original purpose of the Black Stones is unknown.  In recorded history, they have been used as scenes of sacrifice and summonings. Perhaps the Stones form places of power where the dimensional walls are weak.  Alternatively, they might be much more sinister devices. Could they be storing the pain and sufferings of aeons for some dark purpose?


CREATURES OF THE BLACK STONE

The Black Stones seem to have particular affinities with reptilian creatures.  Serpent men once worshipped at the English Black Stone, while in "Worms of the Earth" their degenerate descendents hold a fragment sacred.  At the Hungarian Black Stone, the worshippers summoned a bloated toad-like creature.  On Midsummer's Night, it is said that the awful creature may still be seen.

The name Dagon too seems to be closely associated with the Stones. Thus, it seems likely that the Deep Ones once worshipped at the Black Monoliths as well.  Perhaps more stones are hidden below the dark waves.


SOURCES ON THE BLACK STONE

The players may first hear of the Black Stone from any number of books.  Von Junzt's Nameless Cults mentions the Hungarian Stone briefly, as does Dostmann's Remnants of Lost Empires.  The latter even tells of the village, Stregoicavar, near which the Hungarian Stone is located.  Finally, Justin Geoffrey's "The People of the Monolith" is a poem about the Hungarian Stone, although it gives no hints as to the true location.

It is likely that the British Stone, and perhaps others as well, are told of in books, poems and stories, although Howard gives no hints as to which ones should be perused.


STORY IDEAS FOR THE BLACK STONE

* In dreams, the Hungarian Black Stone is seen set like a spire on a huge black castle.  Perhaps this is literal and a vast fortress does indeed stretch below it.  In any case, it is clear that greater horrors lie below both black stones.  When some creature escapes from the depths, the investigators could be forced to investigate the caverns below.  What terrors might they find?

* There are two known Black Stones, one in Hungary, one in Britain. Perhaps there are others, forming some great symbol across the face of the Earth.  A global campaign might be begun as the investigators travel from one stone to another, trying to halt the steps of a cataclysmic ritual.

* When a small black stone falls into the hands of an investigator, he could find himself the target of a Deep One or Serpent Man trying to recover it.  Alternatively, the investigators might investigate the murder of someone unfortunate enough to have been recently inpossession of a black stone.

* Drawn by the ancient legends, new bands of cultists could come to any of the black stones.  Perhaps they are harmless, or, alternatively, they might unleash something ancient which they are unable to control.

* The investigators might find the key to deciphering the strange writings of the monoliths.  What do they say?  Is it a riddle, a prophecy, a curse?  Who wrote the ancient words?

* One of the stones could be broken.  Serpent Men and Deep Ones are trying to get all the fragments to rebuild it.  This would recreate the magical symbol formed by the stones with the usual possibilities of Earth shattering results.  The investigators must, of course, prevent this. My personal choice of effect would be everyone on the planet suffering nightmares of pain and death until the pattern is disrupted once more. This would give lots of room for further play without the world coming to a total end.