Free OSR Resource From Dragon's Foot - Quann'Ra-Tioll Moorchlyne's Most Excellent Compilation of all the realms known Ioun stones.

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This is fantastic compilation of 600 of the floating treasures known as Ioun stones.
This is one of my all time favorite resources to use in games.Author  Matthew Hargenrader 

does an excellent job with the organization, category, type, and even a few adventure hooks.

What is an Ioun Stone?
According to wiki: 

"Ioun stones (pronounced EYE-oon^[7]) are based on similar artifacts from Jack Vance's Dying Earth series.^[8] When functioning, they float in a circular pattern around their bearer's head, and grant various benefits based on their color and shape. Two stones of the same type will repel each other, and when drained of power, a stone becomes a dull grey, but still possesses the characteristic floating. While useless to a mage, burned out stones can still yield a single psionic power point to a psionic character in 3rd and 3.5 editions. In the original Jack Vance stories IOUN stones are highly prized by arch-magicians, and are acquired from a race known as the archveults, who mine them from remnants of dead stars (in his book Rhialto the Marvellous). In 2E Dungeons & Dragons it had been conjectured in Dragon magazine that Ioun stones instead come from the Positive Material Plane. Dragon #174 featured an article that included many dozens of new types of ioun stone,^[9] as well as an article about an elemental lord who hoards ioun stones on his home plane of radiance."

Using Ioun Stones In Your Old School
Campaign 

I've used Ioun Stones countless times in OSR games. Since they show up in the most unlikely places I've used them in post apocalypse games. In horror games as part of weird alien tech and artifacts. In science fiction as part of alien treasures and hauls.
The stones have also appeared in the wastelands of Mutant Future and as part of the weaponry of dragons in Labyrinth Lord games.
The stones have appeared as weird mechanisms for time travel mechanisms in OD&D and upon Carcosa.
 They have appeared in numerous games including as part of a haul in a Top Secret game and another game involving the Interzone as part of an gemologist's stall.
 I've kept part of the mystery of where they come from but at least some are made from the means that Jack Vance described.
 All in all Quann'Ra-Tioll Moorchlyne's Most Excellent Compilation of all the realms known Ioun stones is a must for any DM wanting to run Ioun Stones in his OSR game!
Having an Exalt for doing such a great free resource!