The challenge of the identification of a new mineral species: example "Pezzottaite"

In 2002, a new gem mineral of commercial importance was discovered. In accordance with the need for all new mineral discoveries to be scientifically characterized (see Nickel and Grice, 1998), the gemological community anxiously awaited the results of tests to positively identify the new mineral (Hawthorne et al., 2003, Hawthorne et al., submitted and Laurs et al., 2003). This period of analysis brought into play the question: Exactly what procedures are necessary for the positive characterization of a new mineral

A new Early Cretaceous lizard in Myanmar amber with exceptionally preserved integument

We here report on a well-preserved juvenile lizard specimen in Albian amber (ca. 110 mya) from the Hkamti site (Myanmar). This new taxon is represented by an articulated skull and the anterior portion of the trunk, including the pectoral girdle and forelimbs. The scleral ossicles and eyelid are also visible, and the specimen exhibits pristine detail of the integument (of both head and body). In a combined molecular and morphological analysis, it was consistently recovered as a scincoid lizard (Scinciformata), as sister to Tepexisaurus + Xantusiidae. However, the phylogenetic position of the new taxon should be interpreted with caution as the holotype is an immature individual. We explored the possibility of miscoding ontogenetically variable characters by running alternative analyses in which these characters were scored as missing data for our taxon. With the exception of one tree, in which it was sister to Amphisbaenia, the specimen was recovered as a Pan-xantusiid. Moreover, we cannot rule out the possibility that it represents a separate lineage of uncertain phylogenetic position, as it is the case for many Jurassic and Cretaceous taxa. Nonetheless, this fossil offers a rare opportunity to glimpse the external appearance of one group of lizards during the Early Cretaceous

Necrophagy by insects in Oculundentavis and other lizard body fossils preserved in Cretaceous amber.

When a vertebrate carcass begins its decay in terrestrial environments, a succession of different necrophagous arthropod species, mainly insects, are attracted. Trophic aspects of the Mesozoic environments are of great comparative interest, to understand similarities and differences with extant counterparts. Here, we comprehensively study several exceptional Cretaceous amber pieces, in order to determine the early necrophagy by insects (flies in our case) on lizard specimens, ca. 99 Ma old. To obtain well-supported palaeoecological data from our amber assemblages, special attention has been paid in the analysis of the taphonomy, succession (stratigraphy), and content of the different amber layers, originally resin flows. In this respect, we revisited the concept of syninclusion, establishing two categories to make the palaeoecological inferences more accurate: eusyninclusions and parasyninclusions. We observe that resin acted as a 'necrophagous trap'. The lack of dipteran larvae and the presence of phorid flies indicates decay was in an early stage when the process was recorded. Similar patterns to those in our Cretaceous cases have been observed in Miocene ambers and actualistic experiments using sticky traps, which also act as 'necrophagous traps'; for example, we observed that flies were indicative of the early necrophagous stage, but also ants. In contrast, the absence of ants in our Late Cretaceous cases confirms the rareness of ants during the Cretaceous and suggests that early ants lacked this trophic strategy, possibly related to their sociability and recruitment foraging strategies, which developed later in the dimensions we know them today. This situation potentially made necrophagy by insects less efficient in the Mesozoic

Pezzottaite - Cs(Be_2Li)Al_2Si_6O_(18) - A Spectacular New Beryl-Group Mineral From The Sakavalana Pegmatite, Fianarantsoa Province, Madagascar

Pezzottaite is a new mineral from the Sakavalana pegmatite, located 25 km south of the village of Mandosonoro, southwest of the town of Antsirabe, 140 km southwest of Ambatofinandrahana, in Fianarantsoa province, central Madagascar. It usually occurs as isolated crystals that can have three distinct habits: (1) irregularly shaped flat masses that fill cavities between "cleavelandite", quartz and tourmaline; (2) subhedral-to-euhedral hexagonal tabular crystals up to 10 cm in diameter; and (3) small flat to equant to elongated crystals attached to faces of large tourmaline crystals. The form {001} is dominant, with minor {100} and {101}; no twinning was observed. Pezzottaite is moderate red (Munsell #15) to pink, with moderate dichroism in polarized light in hand specimen: ω = pink-orange and ε = purplish pink to pinkish purple. The streak is colorless to white, crystals are transparent to translucent with a vitreous luster and no observable fluorescence in long and short-wave ultraviolet light. Crystals are brittle with both conchoidal and irregular fracture, have an imperfect cleavage parallel to {001}, and no observable parting. Mohs hardness is 8, the observed density is 2.97-3.14 g/cm3 and the calculated density is 3.06 g/cm^3. Pezzottaite is uniaxial negative with ε = 1.601-1.611 and ω = 1.612-1.620, depending on Cs content. In transmitted plane-polarized light, it is strongly pleochroic, orange-red ||ε and purple-violet ||ω. Pezzottaite is rhombohedral, space group R3c, with the following unit-cell parameters refined from X-ray powder-diffraction data: a 15.946(4), c 27.803(8)Å, V 6122(2) Å^3, Z = 18. The ten strongest lines in the X-ray powder-diffraction pattern are as follows: d (Å), I, (hkl): 3.271, 100, (036); 2.871, 52, (153); 3.027,41, (146); 3.09, 29, (150); 2.215, 14, (270); 1.636, 14, (0.6.12); 2.229,12, (12.12); 1.749, 12, (36.12); 1.743, 12, (390); 1.518, II, (399). Chemical analysis by electron microprobe and ICP (Li) gave SiO_2 55.55, Al_2O_3 16.00, Se_2O_3 0.03, MnO 0.04, Na_2O 0.19, K_2O 0.04, Rb_2O 0.64, Cs_2) 16.12, Li_2O 2.16, BeO_(ca1c) 7.95, H_2O 0.28, sum 99.00 wt.%, where the amount of H_20 was determined by crystal-structure analysis. The resulting empirical formula, calculated on the basis of 18 structural O atoms, is: (Cs_(0.74)Rb_(0.04)K_(0.01)Na_(0.04))_(Σ0.83)(Be_(2.06)Li_(0.94))Al_(2.04)Si_(6.00)O_(18-) (H_2O)_(0.10). Chemical analysis by LA-ICP-MS gave SiO_2 54.58, TiO_2 0.01, AI_2O_3 16.88, FeO 0.02, Mno 0.02, CaO 0.22, Na_2O 0.46, K_2O 0.14, Rb_2O 0.44, Cs_2O 18.23, Li_2O 2.12, BeO 8.14, sum 101.26 wt.%. The resulting empirical formula, calculated on the basis of 18 structural O atoms, is: (Cs_(0.84)Rb_(0.03)K_(0.02)Na_(0.10))_(Σ0.98)(Be_(2.10)Li_(0.92))_(Σ3.02)Al_(2.00)(Si_(5.86)Al_(0.14))O_(18). The end-member formula of pezzottaite is Cs(Be_2Li)Al_2Si_6O_(18). The mineral is named for Dr. Federico Pezzotta of the Museo Civico, Milano, Italy, for his major role in characterizing the granitic pegmatites of Madagascar. The new mineral and mineral name have been approved by the Commission of New Minerals and Mineral Names of the International Mineralogical Association (2003-022). Pezzottaite is related to the minerals of the beryl group, but differs in having essential Cs and a superstructure that arises from ordering of Be and Li in tetrahedral coordination

Pezzottaite from Ambatovita, Madagascar: A New Gem Mineral

Pezzottaite, ideally Cs(Be_2Li)Al_2Si_6O_(18), is a new gem mineral that is the Cs,Li–rich member of the beryl group. It was discovered in November 2002 in a granitic pegmatite near Ambatovita in central Madagascar. Only a few dozen kilograms of gem rough were mined, and the deposit appears nearly exhausted. The limited number of transparent faceted stones and cat’s-eye cabochons that have been cut usually show a deep purplish pink color. Pezzottaite is distinguished from beryl by its higher refractive indices (typically n_o=1.615–1.619 and n_e=1.607–1.610) and specific gravity values (typically 3.09–3.11). In addition, the new mineral’s infrared and Raman spectra, as well as its X-ray diffraction pattern, are distinctive, while the visible spectrum recorded with the spectrophotometer is similar to that of morganite. The color is probably caused by radiation-induced color centers involving Mn^(3+)