Structural and chemical characterization of dienerite, Ni3As, and its revalidation as a mineral species

ABSTRACT Dienerite, ideally Ni3As, was discovered in 1919 near Radstadt (Salzburg, Austria) and its description and chemical characterization date back to the 1920s. The paucity of reliable experimental data, as well as the absence of any other documented occurrences of such a mineral in over 80 years, led to the supposition of a typographic error in the transcription of the original chemical analysis, suggesting the mineral might in fact be nickelskutterudite [(Ni,Co,Fe)As3]. As a consequence, the mineral was discredited and deleted in the post-2006 IMA list of valid mineral species. Nonetheless, several minerals having a metal/As ratio close to 3:1 and a description fitting that of dienerite were reported after its discreditation. Here we report the discovery of minute inclusions in a sample of josephinite from Josephine Creek (Oregon, USA) exhibiting high optical and electron reflectance. Structural and chemical investigations unequivocally showed that a mineral having cubic structure [a = 9.6206(9) Å, sp. gr. I3d; R1 = 0.0353] and ideal chemical formula Ni3As does exist, suggesting that dienerite could in fact be a valid species. The proposal to revalidate dienerite has been approved by the Commission on New Minerals, Nomenclature and Classification (IMA-Proposal 19-E). The neotype is deposited in the mineralogical collections of the Natural History Museum, University of Florence, Italy, under catalogue number 3364/I.

Des mets et des mots : nommer les mets dans la littérature du XVIe siècle espagnol

The Renaissance believed in the creative power of names. Particularly in 16th-century Spain, there was an effort to put words on a whole series of new realities, particularly those of the New World, where the discovery of new vegetal, animal and mineral species multiplied the need for new terms, or for broadening the scope of those that already existed. Literary texts largely integrated this requirement. Literature was thus going to name the world, especially in a space to which it granted a renewed place: the table, all the more so since the meal makes it possible to immobilise people momentarily, which makes it possible for language to unfolding with greater ease, to really invest the space. Sitting at the dinner table sets the conditions necessary for a discussion to take place. The authors at the time therefore often resorted to it. At the table, the man discusses the most diverse subjects from all over the world. But, inevitably, what he is looking at in front of him, the food, will prevail in his reflection. Hence a marked interest in food vocabulary in the texts, particularly through a real fascination for certain dishes. But naming the dishes also makes it possible to touch on issues that go far beyond food itself: what then do words that talk about dishes really talk about? This is what we will try to identify here.

Pyrochlore-Supergroup Minerals Nomenclature: An Update

The general formula of the pyrochlore-supergroup minerals is A2B2X6Y. The mineral names are composed of two prefixes and one root name (identical to the name of the group). The first prefix refers to the dominant anion (or cation or H2O or vacancy) of the dominant valence at the Y-site. The second prefix refers to the dominant cation of the dominant valence [or H2O or vacancy] at the A-site. Thirty-one pyrochlore-supergroup mineral species are currently distributed into four groups [pyrochlore (B = Nb, X = O), microlite (B = Ta, X = O), roméite (B = Sb5+, X = O), and elsmoreite (B = W, X = O)] and two unassigned members [hydrokenoralstonite (B = Al, X = F) and fluornatrocoulsellite (B = Mg, X = F)]. However, when the new nomenclature system of this supergroup was introduced (2010) only seven mineral species, namely, oxycalciopyrochlore, hydropyrochlore, hydroxykenomicrolite, oxystannomicrolite, oxystibiomicrolite, hydroxycalcioroméite, and hydrokenoelsmoreite, were valid. The seven species belong to the cubic crystal system and space group Fd3¯m and O is predominant in the X structural site. The 24 new mineral species described between 2010 and 2021 are cesiokenopyrochlore, fluorcalciopyrochlore, fluornatropyrochlore, hydrokenopyrochlore, hydroxycalciopyrochlore, hydroxynatropyrochlore, hydroxykenopyrochlore, hydroxymanganopyrochlore, hydroxyplumbopyrochlore, fluorcalciomicrolite, fluornatromicrolite, hydrokenomicrolite, hydroxycalciomicrolite, kenoplumbomicrolite, oxynatromicrolite, oxycalciomicrolite, oxybismutomicrolite, fluorcalcioroméite, hydroxyferroroméite, oxycalcioroméite, oxyplumboroméite, fluornatrocoulsellite, hydrokenoralstonite, and hydroxykenoelsmoreite. Among the new species, hydroxycalciomicrolite belongs to a different space group of the cubic system, i.e., P4232. There are also some mineral species that crystallize in the trigonal system. Hydrokenoelsmoreite occurs as 3C (Fd3¯m) and 6R (R3¯) polytypes. Hydrokenomicrolite occurs as 3C (Fd3¯m) and 3R (R3¯m) polytypes, of which the latter corresponds to the discredited “parabariomicrolite.” Fluornatrocoulsellite crystallizes as 3R (R3¯m) polytype. Surely there are several new pyrochlore-supergroup minerals to be described.

The pascoite family of minerals, including the redefinition of rakovanite

ABSTRACT Mineral species that contain the decavanadate isopolyanion [V10O28]6–, including its protonated and mixed-valence variants, constitute the pascoite family of minerals. Within the pascoite family, the isostructural minerals pascoite and magnesiopascoite form the pascoite group and the isostructural minerals lasalite and ammoniolasalite form the lasalite group. Rakovanite, which was originally assigned the ideal formula Na3[H3V10O28]·15H2O, is redefined with the ideal formula (NH4)3Na3[V10O28]·12H2O.