[Aztlan] Searching for a Slate Disk

[Hoopes, John W]

I'm trying to discover the location of an engraved slate disk of probable Teotihuacan origin that was reportedly recovered from a site in the Caribbean lowlands of Costa Rica in the early 1960s.
 
It appeared as Fig. 22, "Largest engraved disk, Guácimo. Diameter 15.7 cm." in the following publication:
 
Stone, Doris & Carlos Balser (1965) Incised Slate Disks from the Atlantic Watershed of Costa Rica.  American Antiquity, Vol. 30, No. 3 (Jan., 1965), pp. 310-329.
 
It was recovered from Grave 2 in a cemetery at a site referred to as Tres de Guácimo "on property which in 1963 belonged to Ismael Antonio Bermúdez Mora."  According to the authors, "There were about 125 graves at this site and two types of burials.  In the center were some 25 stone mounds .75 to1.5 m high" (p. 317).  Sadly, the location of this site is only approximately known today and it is presumed to have been largely destroyed by looting.
 
According to the article, "This disk bears signs of the gum used to hold the original polygonal pyrites that covered the reverse side before it was reconditioned.  At the time of excavation, however, a plaque of iron pyrites, the surface of which was not beveled toward the back, was attached to the disk.  This plaque has a hole on each side which must have served for suspension before the disk was joined to the engraved slate, but this hole was later plugged with iron pyrites. The pairs of holes furthest from the edge probably also were made later to accomodate fastening the slate, which is a trifle smaller and is beveled toward the back. More precisely, the single pyrites plaque was reconditioned with holes to fit those of the incised slate disk.  On top of the engraved design there are traces of white stucco, which indicate that the slate disk had been covered and re-used according to the reigning fashion (Stone & Balser 1965: 319-320).

This object is not in the collection of the Museo Nacional de Costa Rica (where it should have been deposited).  I suspect it may be in a private or museum collection, but its current whereabouts are unknown.

It is a very distinct object that has a depiction of divers procuring Spondylus shells executed in a Teotihuacan style (complete with speech scrolls).  The article contains a photograph and a detailed description.  Needless to say, it's a very intriguing object!

Any help finding it would be greatly appreciated!

John Hoopes