F ig . 3. Positions of the calcium cations in calcium catapleiite, with an indication of the corresponding occupancies, around the columns of [ZrO 6 ] octahedra running along c . (a) Actual distribution in calcium catapleiite, (b) ordered distribution in calcium catapleiite, and (c) fully

Fig. 5. Gittinsite-bearing (type-II) alteration assemblages after EGM in black kakortokite. Associated alteration minerals include catapleiite (Cat), Sr-rich eudialyte (Sr-Eud), analcime (Anl), fluorite (Fl), annite (Bt), aegirine (Aeg-II), pectolite (Pct), Ca-rich and Ca-poor A1, allanite-(Ce

TABLE 1. CHEMICAL COMPOSITION OF CALCIUM CATAPLEIITE FROM THE BURPALA MASSIF, RUSSIA

TABLE 2. INFORMATION ON DATA COLLECTION AND REFINEMENT FOR CALCIUM CATAPLEIITE

TABLE 3b. DISPLACEMENT PARAMETERS FOR CALCIUM CATAPLEIITE

TABLE 4. SELECTED INTERATOMIC DISTANCES (Å) IN THE STRUCTURE OF CALCIUM CATAPLEIITE

TABLE 5. BOND-VALENCE SUMS ( v.u. ) FOR CALCIUM CATAPLEIITE

F ig . 2. Projection of the crystal structure of calcium catapleiite on (001), drawn with the program ATOMS ( Dowty 1995 ).

adjacent to an unaltered EGM grain, surrounded by arfvedsonite and interstitial nepheline. ( d ) Catapleiite dominated (type-I) pseudomorphs after EGM with replacement of adjacent arfvedsonite by secondary aegirine and Mn-Ti phases. ( e ) Symplectite rim on EGM, consisting of finely-intergrown catapleiite

) and calcio-ancylite-(Ce); ‡ clinochlore and chamosite; ‡‡ catapleiite and calcium catapleiite; † natrolite, edingtonite and an unidentified Na–Ca–Sr zeolite.

. Eudialyte crystals, now replaced mainly by catapleiite, cut across the lamination defined by aegirine-rich layers. Both intitial growth of eudialyte and its replacement must have taken place under static conditions, after eruption. ( c ) and ( d ) Secondary mineral assemblage consisting of fluorite (Flr

) and catapleiite/gaidonnyaite (C/G). Extensively-corroded clinopyroxenes (Cpx-II) are also present within the eudialyte decomposition assemblage. Chlorine released by the decomposing eudialyte reacted with adjacent nepheline (Ne-II) to form sodalite (Sdl). In some places alteration of nepheline (Ne-II

-rich zircon and fractures filled with thorite (white), scale bar 50 μm; (c) cluster of pseudododecahedral crystals of zircon with a Th–Hf-depleted rim, scale bar 200 μm; (d) gittinsite (Gts) overgrown by calcium catapleiite and catapleiite (Ctp); note the relics of zircon (Zrn) and fragments

Fig. 3. (a): Zr K-edge normalised ( k 3 -weighted) EXAFS spectra for the NS3 glasses (solid lines), and the best model calculated for these spectra (dotted lines), based on catapleiite (2 nd spectrum from bottom). The aqueous solution (top-spectrum, showing Zr(H 2 O) 7 moieties) is quite