Guatemalan Jade
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Jadeitites, albitites, eclogites, metabasites and related rocks from Guatemala and elsewhere
This is a long-term field, petrographic and mineralogical study of the occurrence of jadeite rock and other metasomatic inclusions in serpentinite along the Motagua Fault Zone of Guatemala. The study was started to learn about the unusual provenance and mineralogy of jadeite rocks (and associated lithologies) in their limited (8 or so) occurrences world-wide but particularly from the heretofore inadequately studied localities in Guatemala. The goal of this research is to develop an understanding of the crystal chemistry and phase relations of extant minerals and to determine the petrogenesis of these rocks (and their relationship to blueschists and eclogites), the P-T path, the degree of metasomatism/fluid-rock interactions, and the tectonic controls involved (Harlow, 1994a). The study has also extended to the nature and provenance of Middle American jade, the archaeological context of Guatemalan jadeitites (Harlow, 1993). A study was completed on Ba-enrichments in micas that occur in many metasomatic inclusions in serpentinite along the Motagua Fault Zone of Guatemala (Harlow, 1995). More recent developments have been crystallographic studies of the rare Na-Mg mica preiswerkite and taramitic amphiboles, examination of stable isotope systematics (with Craig A. Johnson, U.S.G.S.), and discovery of an eclogite stage of metamorphism in the metabasites from the western end of the metasomatized terrane. A field excursion in the Western Alps in September has led to new interpretations of Guatemalan metabasites; these are now being worked on.
This work has also resulted in a contribution of a short section for The Olmec World exhibition at Princeton University Art Museum (Harlow, 1995). The manuscript addresses the identification and nomenclature of carving materials (rocks) of the artifacts in the exhibition.
References
- Harlow, G.E. (1993) Middle American Jade: Geologic and Petrologic Perspectives on Its Variability and Source. p. 9-29. In Precolumbian Jade: New geological and cultural interpretations, F.W. Lange, ed., Salt Lake City, UT, University of Utah Press, pp. 378.
- Harlow, G.E. (1994) Jadeitites, albitites and related rocks from the Motagua Fault Zone, Guatemala. Journal of Metamorphic Geology 12, 49-68.
- Harlow, G. E. (1995) Rocks and minerals employed by the Olmec as carvings. In The Olmec World: Ritual and Rulership , The Art Museum, Princeton University, Princeton, NJ, pp. 123-4.
