Pezzottaite from Ambatovita, Madagascar: A New Gem Mineral

Abstract

eginning with the 2003 Tucson gem shows, cesium-rich "beryl" from Ambatovita, Madagascar, created excitement among gem collectors and connoisseurs due to its deep purplish pink color (figure 1) and the attractive chatoyancy displayed by some of the material. Although it was sold during and after the Tucson gem shows as "raspberyl," "red beryl," "pink beryl," "hot pinkred beryl," and especially "raspberry beryl," subsequent examinations (see, e.g., Simmons et al., 2003) revealed properties that were anomalous for beryl and were associated with very high concentrations of cesium (Cs). In September 2003, the International Mineralogical Association approved the name pezzottaite (pe-zó-ta-ite) for this new species of the beryl group. It is named after Dr. Federico Pezzotta (Natural History Museum, Milan, Italy), who was among the first to investigate this new mineral, in recognition of his scientific contributions to the mineralogy of Madagascar (Hawthorne et al., 2003). With the addition of pezzottaite-ideally Cs(Be 2 Li)Al 2 Si 6 O 18-the beryl group consists of four members. The other three (all hexagonal) are: beryl (Be 3 Al 2 Si 6 O 18 ; Aurisicchio et al., 1988), bazzite (Be 3 Sc 2 Si 6 O 18 ; Armbruster et al., 1995), and stoppaniite (Be 3 Fe 2 Si 6 O 18 ; Ferraris et al., 1998; Della Ventura et al., 2000). Pezzottaite, which is rhombohedral, is not a Cs-rich beryl but rather a new mineral species that is closely related to beryl. Another mineral, indialite ([Al 2 Si]Mg 2 [Al 2 Si 4 ]O 18 ; Meagher and Gibbs, 1977), is also sometimes included in the beryl group. Of these, only beryl and pezzottaite have been found in gem quality. (Note: In this article, "beryl" refers to the mineral species, rather than the group, unless otherwise specified.) Pezzottaite has been confirmed from just one deposit in Madagascar, the Sakavalana granitic pegmatite located near Ambatovita in a remote area of the central highlands. In addition to material from this locality, a sample of Cs-rich "morganite" from Afghanistan described by Hänni and Krzemnicki (2003) has now been recognized as pezzottaite (H. Hänni, pers. comm., 2003). Observations of the crystal morphology of pezzottaite from Madagascar 284

Iron+magnesium-Bearing Beryl From Granitic Pegmatites: An Empa, La-Icp-Ms, Mössbauer Spectroscopy, and Powder XRD Study

“…4). It does not fit with their expected positive behavior (Aurisicchio et al 2012) because the substitution CH Cs T2 Li = CH □ T2 Be is dominant exclusively in Cs-rich beryl and pezzottaite from evolved pegmatites (e.g., Laurs et al 2003). Consequently, the concentrations of Li and Cs in beryl are constrained chiefly by their availability in the system and structural parameters obviously do not control their contents.…”

“…Chemical compositions of beryl from granitic pegmatites have been presented in numerous papers; however, the research was focused chiefly on Fe-poor beryl and its Cs,Na,Li-enriched varieties and pezzottaite (e.g., Černý et al 2003a, Laurs et al 2003, Wang et al 2009, Aurisicchio et al 2012, whereas Fe,Mg-enriched beryl has been studied rather scarcely (e.g., Schaller et al 1962, Aurisicchio et al 1988, 2012, Uher et al 2010, Novák & Filip 2010. Moreover, Mössbauer spectroscopic studies of Fe in beryl (aquamarine) from granitic pegmatites in Brazil (e.g., Viana et al 2002, da Costa et al 2006) provide only very brief information about the examined samples, host pegmatites, and their mineral assemblages.…”

Raman and structural comparison between the new gemstone pezzottaite Cs(Be2Li)Al2Si6O18 and Cs‐beryl

“…A gem quality, transparent, and pink crystal of pezzottaite (about 4 cm 3 ) from the Sakavalana pegmatite (northern part of the famous Ampandramaika‐Malakialina pegmatite district, locality of Ambatovita – central Madagascar) was used for this study. The second sample (~5 cm 3 ) is a pale‐pink crystal of Cs‐beryl (‘morganite’ variety) from the Pastori vein in Fosso Marcianella pegmatite, San Piero in Campo (Elba Island).…”

Contributed Papers in Specimen Mineralogy: Part 1

“…The material made its debut at the 2003 Tucson Gem and Mineral Show and was marketed under such names as "raspberyl" and "hot pink beryl." Subsequently, it was identified as a new mineral that possesses high specific gravity and refractive index values in comparison to beryl (Laurs et al 2003). Electron microprobe analyses show that the Cs 2 O content ranges from 11 to 18 weight percent.…”