PETROLOGY OF MOLDAVITES

During the systematic petrological examination of 311 Bohemian and 130 Moravian moldavites, layered Muong Nong type specimens were found to be fairly common. In these layered forms mineral grains which appear to be detrital were found in one specimen, another contains thin bubbles of irregular angular outline, and other specimens contain rayed bubbles and elongate ray clusters. Schlieren and objects of both higher and lower refractive index than the enclosing glass occur in splash form moldavites, and lechatelierite particles of varied shape and surface configuration are found in both splash and layered forms. When values for petrological properties of moldavites (refractive index, specific gravity, lechatelierite abundance, lechatelierite size, lechatelierite shape, bubble abundance, bubble size, bubble shape, strength of flow structure, strength of flow structure strain, and strength of overall strain) are averaged by groups of localities and plotted on a map of Czechoslovakia, a systematic direction of variation is found for the Bohemian part of the strewn-field but not for the Moravian part. On the basis of these properties for the strewn field as a whole, the central part of the strewn-field is postulated to be in the vicinity of the Moravian area of moldavite occurrence. Local melting probably took place over an area at least twice the diameter of the present known area of moldavite distribution. © 1969.