...TABLE 5. REPRESENTATIVE RESULTS OF ELECTRON-MICROPROBE ANALYSES OF LORENZENITE AND LANDAUITE, KATZENBUCKEL VOLCANO, SOUTHWESTERN GERMANY ...

... with I > 3σ( I ). Almeidaite is a member of the crichtonite group with Pb dominant in the A site (with 12-fold coordination) and Zn dominant in the T site (with 4-fold coordination). It is a Zn analogue of senaite and a Pb analogue of landauite. The mineral is named after Professor Fernando Flávio...

..., related to crichtonite, landauite and davidite-(Ce,La), may represent potentially new members of the crichtonite group. They display compositional zoning, and are associated with diverse oxide minerals, albite and alkali feldspar. Our compositions (EMP) suggest that the “large cations” (Sr, Na, K...

... of the AM 21 O 38 series, characterized by predominant A-specific, large cations (Sr = crichtonite; Na = landauite; Pb = senaite; Ca = loveringite, and U + REE = davidite), and by M-formula small cations which are dominantly Ti, Cr, Fe, Mg, Zr, and Nb. Approximately 70% of the A-site is filled by either Ba...

..., mainly titanium and iron, occupy a tetrahedral site, M(2), and three other octahedral sites, M(3), M(4), and M(5). A comparison is made of the site occupancies and average metal-oxygen bond lengths for five crichtonite-group minerals—senaite, crichtonite, davidite, loveringite, and landauite. A linear...

... ( Zhang et al. , 1988 ), senaite ( Grey & Lloyd, 1976 ), dessauite-(Y) ( Orlandi et al. , 1997 ), landauite ( Grey & Gatehouse, 1978 ), gramaccioliite-(Y) ( Orlandi et al. , 2004 ) and the new mineral cleusonite ( Table 1 ). Crichtonites are characterised by a common structural formula: XII_...

... the crichtonite group is characterized by an unique combination of dominant A and B cations. The minerals so far known within this group are crichtonite, senaite, davidite-(La), davidite-(Ce), davidite-(Y), loveringite, landauite, linds-leyite, mathiasite, dessauite-(Y), and the new mineral “IMA 1998–070” ( Table...

... 0.14 Sr 0.10 ) ∑l.0 [Ti 12.90 Cr 3.l0 Mg 1.53 Fe 2.15 Zr 0.67 Ca 0.29 (V,Nb,Al) 0.36 ] ∑2l.0 O 38 . Acta Cryst. , C39 , 421 – 422 . Grey I.E. Gatehouse B.M. ( 1978 ): The crystal structure of landauite, NaMnZn 2 (Ti,Fe) 6 Ti 12 O 38 . Can. Mineral. , 16 , 63 – 68 . Grey...

... to their various chemical compositions. As a result, in addition to the early defined species, such as crichtonite ( Grey et al. , 1976 ), senaite ( Grey & Lloyd, 1976 ), landauite ( Grey & Gatehouse, 1978 ), loveringite ( Gatehouse et al. , 1978 ), davidite-(Ce) and davidite-(La) ( Gatehouse et al...

... et al . (1997) Gramaccioliite-(Y) 2.813 2.225 1.957 2.015 1.967 1.980 Orlandi et al . (2004b) Landauite 2.822 2.211 1.963 1.997 1.973 1.969 Grey & Gatehouse (1978) Lindsleyite 2.837 2.119 1.948 1.982 1.990 1.978 Zhang et al . (1988) Loveringite 2.789...

... 3 ) 2 (OH) 6 4 1O,3OH APEG X 15 6 2O, 4OH Franklinite Spinel ZnFe 2 3+ O 4 4 4O X X 4 Landauite Crichtonite Na[MnZn 2 (Ti,Fe) 6 Ti 12 ]O 38 4 4O 1.964 16 Murataite (Y,Na) 6 (Zn,Fe 3+ ) 5 (Ti,Nb) 12 (O,□) 29 (O,F) 10 F4 5 5O 2.04 Fe 3+ , Ti...

... are cleusonite, crichtonite, davidite-(La), davidite-(Y), davidite-(Ce), dessauite-(Y), gramaccioliite-(Y), landauite, lindsleyite, loveringite, mathiasite, and senaite (Table 1 ; cf. Wülser et al ., 2005 ). Table 1. Main cations on the M0 (=A) and M1 (=B) structural sites of the crichtonite group...

... Fe 2 O 38 ; (Na,Sr,K,REE)(Zr,Ca,Mn)(Ti,Fe) 18 Fe 2 O 38 . Formulae 1 and 2 correspond to potentially new Ca- or Zr-dominant variants of crichtonite, whereas 3 and 4 correspond to potentially new Ca- or Zr-dominant variants of landauite. Georgbarsanovite (collected prior to 1963) came...

... is also present as H 2 O-free minerals such as willemite, genthelvite, landauite, murataite, nordite and osumillite. Subsolidus, low-temperature autohydration processes result in sequestration of Zn in clay minerals, zeolites and labuntsovite-group minerals. These observations are at variance...

..., pyrophanite, Sr-perrierite, landauite, rutile, anatase, bookite), REE minerals (loparite, metaloparite, britholite, rinkolite, melanocerite, bastnäsite, parisite, fluocerite, ancylite, monazite, REE‑apatite), Nb- and Ta-minerals (pyrochlore, blomstrandite, loparite, four varieties of metaloparite), and other...

... ; Gatehouse et al. , 1978 ). Other crichtonite-group minerals such as crichtonite sensu stricto with A = Sr ( Grey et al. , 1976 ), dessauite with A = Sr, Pb ( Orlandi et al. , 1997 ), landauite with A = Na ( Grey and Gatehouse, 1978 ) and davidite with A = Ln , Th, U, Y, Sr, Pb ( Gatehouse et al...