IMA 2009-010 = devitoite

[Marco E. Ciriotti]

La descrizione-tipo di IMA = devitoite è annunciata come prossimamente sul Canadian Mineralogist.

Referenza:
• Kampf, A.R., Rossman, G.R., Steele, I.M., Pluth, J.J., Dunning, G.E., Walstrom, R.E. (2010): Devitoite, a new heterophyllosilicate with astrophyllite-like layers from eastern Fresno County, California. Canadian Mineralogist, 48, (in press).


Devitoite [Ba6(PO4)2(CO3)] [Fe2+7(OH)4Fe3+2O2(SiO3)8] tric P1 5.3437 11.6726 14.680 85.573 83.243 76.768

La specie è stata dedicata al micromounter Alfred (Fred) DeVito (1937-2004).

[Marco E. Ciriotti]

Riporto qui quanto postato da Alfredo Petrov su mindat:

""Fred DeVito did an enormous amount of mineralogical exploration in Fresno County and truly deserved this honor, but unfortunately did not live to see it happen. I know this is not the right thread for obituary notices, but one thing needs to be said about this man's character: After his death, when his collection was dispersed, there were few pieces of high quality, although many fellow collectors (including myself) had received wonderful pieces from him as gifts and in trades. Fred gave away his better pieces and kept lesser pieces for himself! Of how many collectors could this be said?""

[Marco E. Ciriotti]

Qui acclusa una foto della nuova specie (devitoite).

[Marco E. Ciriotti]

Referenza:
• Kampf, A.R., Rossman, G.R., Steele, I.M., Pluth, J.J., Dunning, G.E., Walstrom, R.E. (2010): Devitoite, a new heterophyllosilicate with astrophyllite-like layers from eastern Fresno County, California. Canadian Mineralogist, 48, 29-40.

Abstract:
Devitoite, [Ba6(PO4)2(CO3)] [Fe2+7Fe3+2(Si4O12)2O2(OH)4], is a new mineral species from the Esquire #8 claim along Big Creek in eastern Fresno County, California, U.S.A. It is also found at the nearby Esquire #7 claim and at Trumbull Peak in Mariposa County. The mineral is named for Alfred (Fred) DeVito (1937–2004). Devitoite crystallized very late in a sequence of minerals resulting from fluids interacting with a quartz–sanbornite vein along its margin with the country rock. The mineral occurs in subparallel intergrowths of very thin brown blades, flattened on {001} and elongate and striated parallel to [100]. The mineral has a cream to pale brown streak, a silky luster, a Mohs hardness of approximately 4, and two cleavages: {001} perfect and {010} good. The calculated density is 4.044 g/cm3. It is optically biaxial (+), 1.730(3), β 1.735(6), 1.755(3); 2Vcalc = 53.6°; orientation: X b, Y c, Z a; pleochroism: brown, Y >>> X > Z. Normalized electron-microprobe analyses provided: BaO 38.83, CaO 0.50, MgO 0.75, FeO 22.02, Fe2O3 6.08, Al2O3 1.50, SiO2 20.97, TiO2 0.80, P2O5 4.84, H2O 1.67, CO2 2.04, total 100.00 wt%, with FeO and Fe2O3 assignments and H2O and CO2 based on the structure. The empirical formula is [(Ba5.45 Ca0.19)5.64(PO4)1.47O0.30(CO3)] [(Fe2+6.60Mg0.40)7(Fe3+1.64Ti4+0.22Al3+0.14)2(Si7.51Al0.49)8O26(OH)4]. Devitoite is triclinic, P-1, a 5.3437(7), b 11.6726(15), c 14.680(2) Å, 91.337(4), β 96.757(4), 103.233(4)°, V 884.0(2) Å3 and Z = 1. The crystal-structure determination (R1 = 9.56% for 1370 Fo > 4F) shows the mineral to be a heterophyllosilicate with astrophyllite-type HOH layers in which five-coordinated Fe3+ takes the place of Ti4+. The interlayer region contains Ba atoms, PO4 groups and CO3 groups. The configuration of the Ba and PO4 in the interlayer region is similar to that found in the structure of yoshimuraite.

[Marco E. Ciriotti]

L'attenta lettura della descrizione-tipo della devitoite permette di scoprire come i dati di cella forniti nella descrizione-tipo della yoshimuraite (le due specie sono correlate) siano in parte errati.

I dati esatti sono i seguenti: tric P1 5.386 6.999 14.748 95.50 93.62 89.98 2

Nella località tipo (s.l.) sono state rinvenute ad oggi ben 13 nuove specie (da Trumbull Peak, sanbornite e fencooperite; da Big Creek e Rush Creek, fresnoite, krauskopfite, macdonaldite, muirite, traskite, verplanckite, walstromite, alforsite, bigcreekite, kampfite e devitoite) e altre sono attualmente allo studio; tra queste una fase Fe2+ analoga della ericssonite e lo Fe2+,Al analogo della cerchiaraite!