The Mossbauer spectra of prasiolite and amethyst crystals from Poland

Mössbauer spectroscopy of green (prasiolite) and violet (amethyst) quartz crystals from the Sudety Mountains (Poland) has shown that neither Fe2+ nor Fe4+ ions are present in them. Only Fe3+ ions have been identified and only in interstitial positions in channels parallel or perpendicular to the c-axis. The valence of Fe3+ ions did not change as a result of irradiation or annealing. Instead, we believe that the Fe3+ ions move within channels or between them

Chrysoprase – history and present

The authors present the history of chrysoprase discovery and the progress of knowledge about this material over the millennia, based on the extended review of world literature. Tracing the oldest archaeological artifacts from before 9,000 years, the lens of history turns on a stone that has not been properly identified mineralogically for centuries. In the 1830s, chrysoprase was finally included into the chalcedony group and its green color was associated, very correctly, with nickel compounds dispersed in its structure. After all, the most current mineralogy of chrysoprase is presented on the basis of the results of modern analytical studies. These data clearly indicate that chrysoprase is a mixture of several SiO2 polymorphs with varying degrees of structural order (opal, chalcedony, moganite, quartz). This radically changes the previous taxonomy of chrysoprase and its position in current mineralogical and petrographic systematics

Chrysoprase – history and present

The authors present the history of chrysoprase discovery and the progress of knowledge about this material over the millennia, based on the extended review of world literature. Tracing the oldest archaeological artifacts from before 9,000 years, the lens of history turns on a stone that has not been properly identified mineralogically for centuries. In the 1830s, chrysoprase was finally included into the chalcedony group and its green color was associated, very correctly, with nickel compounds dispersed in its structure. After all, the most current mineralogy of chrysoprase is presented on the basis of the results of modern analytical studies. These data clearly indicate that chrysoprase is a mixture of several SiO2 polymorphs with varying degrees of structural order (opal, chalcedony, moganite, quartz). This radically changes the previous taxonomy of chrysoprase and its position in current mineralogical and petrographic systematics

Gemstones from the ducal part of the fortified settlement of Poznań (10th/11th century) in the light of gemological studies and micro-Raman spectroscopy

During archaeological excavations in Poznań there were discovered a ducal palace, a chapel dated to the 10th century, and goldsmith’s workshop adjacent to them. In the layer of ashes at the bottom of the manufacture, there were fragments of gold found together with numerous glass beads and gems. Fourteen gems, made of rock crystal, agate, carnelian, milky chalcedony, garnet, were chosen for gemstone analysis and micro-Raman spectroscopy. The study material is dominated by beads (12 samples, of which six is faceted and six globular), while two pyrope samples have the cabochon cut. It should be emphasized that the rock crystal gems in the collection are usually heptagonal. Majority of the Poznań collection is of high quality, which is a sign of an advanced grinding and faceting technology. Pyrope from the Poznań collection contains inclusions of apatite, rutile, quartz, and magnetite, identified with micro-Raman spectroscopy. A similar combination of inclusions was recognized in pyrope from deposits in Vestřev near Turnov (Bohemia), and hence it indicates that the artifacts from Poznań were made of the pyrope from those deposits. Considering inclusions in rock crystal artifacts from the Poznań collection it was assumed that the mineral was also of the Bohemian origin