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

Spatial and Sex-Specific Variation in Growth of Albacore Tuna (Thunnus alalunga) across the South Pacific Ocean

Spatial variation in growth is a common feature of demersal fish populations which often exist as discrete adult sub-populations linked by a pelagic larval stage. However, it remains unclear whether variation in growth occurs at similar spatial scales for populations of highly migratory pelagic species, such as tuna. We examined spatial variation in growth of albacore Thunnus alalunga across 90° of longitude in the South Pacific Ocean from the east coast of Australia to the Pitcairn Islands. Using length-at-age data from a validated ageing method we found evidence for significant variation in length-at-age and growth parameters (L∞ and k) between sexes and across longitudes. Growth trajectories were similar between sexes up until four years of age, after which the length-at-age for males was, on average, greater than that for females. Males reached an average maximum size more than 8 cm larger than females. Length-at-age and growth parameters were consistently greater at more easterly longitudes than at westerly longitudes for both females and males. Our results provide strong evidence that finer spatial structure exists within the South Pacific albacore stock and raises the question of whether the scale of their “highly migratory” nature should be re-assessed. Future stock assessment models for South Pacific albacore should consider sex-specific growth curves and spatial variation in growth within the stock

Yellow muscovite from Brazil

Micas are rarely faceted due to their softness (Mohs 2½) and perfect cleavage, but occasionally compact aggregates showing an attractive color are polished into beads, carvings, objets d’art, or even faceted stone. At the 2010 Tucson gem shows, a new gem-quality yellow mica debuted from Itinga in the Araçuaí pegmatite district, Minas Gerais, Brazil (e.g., figure 23). It was sold as yellow lepidolite by most dealers or as muscovite (M. Macrì, “Lepidolite gialla di qualità gemma,” Rivista Gemmologica Italiana, Vol. 5, No. 3, 2010, pp. 234– 235). A faceted stone and cabochon were donated to the GIA Collection by Mauro Pantò (The Beauty in the Rocks, Laigueglia, Italy). Mr. Pantò has polished approximately 1,000 carats of faceted stones and 2,000 carats of cabochons, ranging from 4 to 12 ct

Yellow-green clinohumite and yellow chondrodite from Tanzania

During a buying trip to Tanzania in 2006, gem dealer Farooq Hashmi obtained some brownish yellow and yellow-green rough from a few small parcels that were represented as tourmaline from a new deposit at Sumbawanga in west-central Tanzania. All of the rough consisted of broken pieces (figures 20 and 21), so it was not possible to determine if they originated from primary or secondary deposits. Most of the pieces weighed <1 g, and there was an approximately equal percentage of the two colors available in each parcel. The appearance and properties of the material were not typical of tourmaline normally found in Tanzania, so Mr. Hashmi loaned several rough and cut examples of each color for examination at GIA

Yellow Mn-rich tourmaline from the canary mining area, Zambia

The most important source of yellow gem elbaite is the Canary mining area in the Lundazi District of eastern Zambia. The tourmaline has been mined since 1983 from both pegmatite and eluvial/alluvial deposits, in colors typically ranging from yellow-green to yellow to orange and brown; much of the orange-to-brown material is heated to attain a "golden" or "canary" yellow color. The tourmaline is Mn-rich (up to 9.18 wt.% MnO documented in the literature) and contains traces of Ti and little or no Fe. The distinctive composition of this tourmaline is probably the result of the crystallization of abundant schorl from an unusual B-rich, Li-poor pegmatite magma, which depleted Fe while conserving Mn until the late-stage crystallization of gem pockets

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+)