Alberiniite, Fe2+(SO3)·3H2O, a new sulfite mineral species from the Monre Falò Pb-Zn mine, Coiromonte, Armeno municipality, Verbano Cusio Ossola province, Piedmont, Italy

Albertiniite, Fe2+(SO3)·3H2O, is a new Fe2+ 47 sulfite trihydrated, chemically related to 48 gravegliaite. It occurs at the Monte Falò Pb-Zn mine near Coiromonte, in the Armeno municipality, 49 Verbano-Cusio-Ossola province, Italy. It is an intermediate product of oxidation between iron 50 sulphides and sulphates, forming monoclinic, colourless to pale yellow transparent crystals with 51 vitreous lustre. The mineral occurs associated with stolzite, pyromorphite, hinsdalite, 52 plumbogummite, gibbsite, scheelite, and jarosite on brittle fractures of quartz veins or chlorite- 53 schist. Albertiniite is optically biaxial positive (+) with 2V(meas) ~ 40° and 2V(calc) = 66°. The 54 measured refractive indices, using sodium light (589 nm), are: ? = 1.612(2) °, ? = 1.618(2) °, and ? 55 = 1.632(2) °. The optical axis plane is parallel to the perfect {010} cleavage plane. It is non 56 fluorescent under short-wave (254 nm) or long-wave (366 nm) ultraviolet light. The calculated density is 2.469 g/cm3 (from the crystal-structure refinement), or 2.458 g/cm3 57 (from the chemical 58 analysis and the single-crystal unit-cell parameters). The empirical formula is (average of 16 spots 59 and based on 3 anhydrous oxygen a.p.f.u.) : (Fe2+ 0.774Mn2+ 60 0.282Ca0.001Mg0.001Na0.003)?1.061(S0.971O3)?2.84H2O, with the H2O content calculated by 61 difference to 100 wt%. Albertiniite is monoclinic with space group P21/n. Its unit-cell parameters are: a = 6.633(1) Å, b = 8.831(1) Å, c = 8.773(1) Å, ? = 96.106(8) ° and V = 511.0(1) Å3 62 ,with Z = 63 4. The eight strongest measured lines in the X-ray powder diffraction pattern are [d in Å, (I/I0), 64 (hkl)]: 4.072 (100) (-111), 3.539 (93) (-112), 5.533 (27) (-101), 6.167 (14) (011), 2.830 (14) (211), 65 4.998 (14) (101), 4.353 (12) (111), and 3.897 (12) (012). The mineral, which has been approved by 66 the CNMNC under number IMA2015-004, is named albertiniite in honour of Claudio Albertini, an 67 Italian mineral collector expert in the systematic mineralogy of Alps and pegmatites.