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

Albertiniite, Fe2+(SO3)·3H2O, is a new Fe2+ sulfite trihydrated, chemically related to gravegliaite. It occurs at the Monte Falò Pb-Zn mine near Coiromonte, in the Armeno municipality, Verbano-Cusio-Ossola province, Italy. It is an intermediate product of oxidation between iron sulphides and sulphates, forming monoclinic, colourless to pale yellow transparent crystals with vitreous lustre. The mineral occurs associated with stolzite, pyromorphite, hinsdalite, plumbogummite, gibbsite, scheelite, and jarosite on brittle fractures of quartz veins or chloriteschist. Albertiniite is optically biaxial positive (+) with 2V(meas) ~ 40° and 2V(calc) = 66°. The measured refractive indices, using sodium light (589 nm), are: ? = 1.612(2) °, ? = 1.618(2) °, and ? = 1.632(2) °. The optical axis plane is parallel to the perfect {010} cleavage plane. It is non 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 (from the chemical analysis and the single-crystal unit-cell parameters). The empirical formula is (average of 16 spots and based on 3 anhydrous oxygen a.p.f.u.) : (Fe2+0.774Mn2+ 0.282Ca0.001Mg0.001Na0.003)?1.061(S0.971O3)?2.84H2O, with the H2O content calculated by 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,with Z = 4. The eight strongest measured lines in the X-ray powder diffraction pattern are [d in Å, (I/I0), (hkl)]: 4.072 (100) (-111), 3.539 (93) (-112), 5.533 (27) (-101), 6.167 (14) (011), 2.830 (14) (211), 4.998 (14) (101), 4.353 (12) (111), and 3.897 (12) (012). The mineral, which has been approved by the CNMNC under number IMA2015-004, is named albertiniite in honour of Claudio Albertini, an Italian mineral collector expert in the systematic mineralogy of Alps and pegmatites.