A multiyear investigation of jadeite was undertaken in an effort to establish the characteristic properties of the Motagua source material, and to ascertain its relationship to jadeite artifacts from selected archaeological sites throughout the the Maya zone. A more limited analysis of jadeite and related materials from Costa Rica has been carried out in order to place Maya jadeite in a broader perspective. The characterization has been achieved through a determination of elemental composition by neutron activation analysis coupled with identification of mineralogical components by means of x-ray diffraction and petrographic thin-section examination.