... Carbonates in the system Na 2 CO 3 -CaCO 3 are nowadays suggested as having a wide stability field at conditions of the mantle transition zone. Our structural analysis of nyerereite, which has limited stability fields at ambient conditions, and its similarities with already known carbonates that are stable...

...F. Kaminsky; R. Wirth; S. Matsyuk; A. Schreiber; R. Thomas Abstract Nyerereite and nahcolite have been identified as micro- and nano-inclusions in diamond from the Juina area, Brazil. Alongside them are Sr- and Ba-bearing calcite minerals from the periclase-wüstite series, wollastonite II (high...

.... The carbonatite samples contain two mineral assemblages: the first consists of relict primary magmatic minerals: nyerereite, fluorite, apatite-(CaF), barite, magnetite and khanneshite. The second consist of low-temperature subsolidus minerals: pirssonite, calcite, shortite, nahcolite, trona, thermonatrite...

... in the groundmass of the host kimberlite. Rasvumite occurs in chloride–“nyerereite” and carbonate clasts, where it forms prismatic crystals (up to 5 mm) or is associated with djerfisherite in a rim around pyrrhotite. Djerfisherite is the omnipresent sulfide in all types of chloride-containing clasts, in which...

...R. H. Mitchell Abstract Natrocarbonatite lavas erupted from hornitos T37B and T49B at Oldoinyo Lengai (Tanzania) during 23–30 July, 2000 are unusual in containing sylvite and fluorite microcrysts together with fluorite-nyerereite intergrowths. The latter are relatively coarse grained and exhibit...