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

Albertiniite, Fe2+(SO3)∙3H2O, is a new Fe sulfite trihydrated mineral species, chemically related to gravegliaite. It occurs at the Monte Falò Pb-Zn mine near Coiromonte, in the Armeno municipality, Verbania province, Italy. It is an intermediate product of oxidation between Fe sulphides and Fe sulphates forming monoclinic, colorless to pale yellow transparent crystals with vitreous lustre. The mineral occurs associated to stolzite, pyromorphite, hinsdalite, plumbogummite, gibbsite, scheelite, and jarosite on brittle fractures of quartz veins or chlorite-schist. Albertiniite is biaxial positive (+) with 2V(meas)  40° and 2V(calc) = 66°. The measured refractive indices, using sodium light (589 nm), are: α = 1.612(2) °, β = 1.618(2) °, and γ = 1.632(2) °. The optical axis plan is parallel to the perfect {010} cleavage plane. It is non fluorescent 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, based on 3 (non-H2O) oxygen a.p.f.u., is : (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 (93.4) (-1 1 2), 5.533 (27.2) (-101), 6.167 (14.1) (011), 2.830 (14.1) (211), 4.998 (13.6) (101), 4.353 (12.5) (111), and 3.897 (11.8) (012). The mineral, which has been approved by the CNMNC under number IMA 2015-004, is named albertiniite in honour of Claudio Albertini.