The thing was about the size of a small orange and was slightly flattened at the ends, like a planet at its poles. It puzzled Tregardis, for it was not like an ordinary crystal, being cloudy and changeable, with an intermittent glowing in its heart, as if it were alternately illumed and darkened from within… It was unique and without fellow in any land or time. In its depths, all former years, all things that have ever been, were supposedly mirrored, and would reveal themselves to the patient visionary… Before him, on a table of some dark Hyperborean wood that had been graven with grotesque ciphers, the crystal appeared to swell and deepen, and in its filmy depth he beheld a swift and broken swirling of dim scenes, fleeting like the bubbles of a millrace.
Ubbo-Sathla by Clark Ashton Smith
The Crystal of Zon Mezzamalech was acquired by that sorcerer, inhabitant of Mhu Thulan in Hyperborea, "in dubitable ways, from a more than sinister source." After his disappearance it is believed to have passed to the wizard Eibon before vanishing after he also disappeared.
It was then unearthed by "a geologist in Greenland, beneath glacial ice, in the Miocene strata." (the Mathieson expedition from Miskatonic University in 1924?) At some point after the expedition it passed into the hands of a Jewish dealer in antiquities and curios in London, who sold it to Paul Tregardis, a wealthy student of anthropology and the occult, in the winter of 1932.
Following Paul's disappearance in early 1933, the crystal may have been stolen or acquired by Dr. Williem
Eisenbein, who was in England in or before 1937 experimenting with Tillinghast Radiation and sonic weapons before fleeing to Germany and joining the Karotechia in 1939.
From him, it passed to SS General Dr Hans Kammler, probable Karotechia member, and was used in his experiments with the device known as the Nazi Bell. After Kammler fled to Antarctica, where he was probably killed by Operation HIGHJUMP (or possibly Delta Green's later Operation SOUTHERN HOSPITALITY), little more is known of the Crystal. It has been suggested that it has something to do with the Crystal AIs that Majestic-12 acquired from the Greys. There may also have been a sighting in Hillston, Colarado during the 1990s.