Jadeite from Guatemala: New Observations and Distinctions Among Lavender and Black Jade

This study systematically investigates the mineralogical, spectral, and geochemical characteristics of Guatemalan lavender jadeite and black omphacite to elucidate their coloration mechanisms and genetic origins. Lavender samples are primarily composed of jadeite, which derives its color from synergistic effects involving Mn3+ and Fe2+-Ti4+ charge transfer (554–614 nm). In contrast, black samples are dominated by omphacite, which owes its dark hue to Cr3+ (670 nm) and Fe2+-Fe3+ charge transfer (857 nm). Chemically, lavender jadeite exhibits higher Na2O and Al2O3, approaching the jadeite end-member composition, whereas black omphacite is enriched in CaO, MgO, and FeO. Trace element analyses reveal low overall abundances, with black omphacite showing synchronous LREE and HREE depletion forming a “bulge-shaped” pattern, while lavender jadeite displays N-MORB-like REE distributions. Guatemalan jadeites are distinguished from Myanmar counterparts by Y enrichment. The identification of graphite and CH4 and CO2 fluid inclusions indicates formation in an organic-rich reducing environment. Cathodoluminescence zoning and abundant fluid inclusions support a direct crystallization genesis from high-pressure fluids (P-type) in subduction zones. This study establishes key constraints for origin discrimination and genetic classification of Guatemalan lavender jadeite and black omphacite.