New Minerals from the Redmond Mine, North Carolina, USA: IV. Haywoodite and Hanahanite, Two New Minerals Containing Gordaite-Like Sheets

The new minerals haywoodite, [Pb(H₂O)₁₀)][Zn₁₂(OH)₂₀(H₂O)(SO₄)₃] (IMA2021-115), and hanahanite, [Zn₈(OH)₁₄(SO₄)]·3H₂O (IMA2022-012), were found in the Redmond mine, Haywood County, North Carolina, USA, where they occur in a highly unusual secondary assemblage that comprises a variety of rare Pb-Zn-Cu sulfates, thiosulfates, and carbonates. Haywoodite has the following properties: colorless to pale pink pseudohexagonal tablets and barrel-like prisms up to about 0.5 mm in diameter; white streak; vitreous luster; brittle; Mohs hardness 2½; curved and stepped fracture; one perfect cleavage on {011}; 3.27(2) g/cm³ measured density; biaxial (−) with 1.588(2), β = 1.600(2), γ = 1.607(2), and 2V (meas.) = 76(2)°. Hanahanite has the following properties: light blue prisms up to 0.3 mm in length; white streak; vitreous luster; brittle; Mohs hardness 3; curved fracture; one very good cleavage on {001}; 3.28(2) g/cm³ measured density; uniaxial (−) with ω = 1.636(3) and ε = 1.620(3). Electron probe microanalyses provided the empirical formulae Pb_1.36Zn_11.97S_3.00O₄₃H_41.33 and (Zn_6.69Cu_1.27Co_0.01)_Σ7.97S_1.00O₂₁H_20.04 for haywoodite and hanahanite, respectively. Haywoodite is triclinic, P1¯, a = 8.35298(19), b = 13.2769(7), c = 18.2744(13) Å, α = 92.427(8), β = 90.419(6), γ = 108.214(4)°, V = 1922.94(18) ų, and Z = 2. Hanahanite is hexagonal, P6₃, a = 8.312(2), c = 15.295(2) Å, V = 915.2(5) ų, and Z = 2. The structures of haywoodite (R₁ = 0.037 for 6876 I > 2σI) and hanahanite (R₁ = 0.065 for 772 I > 2σI) both contain gordaite-like sheets. In the haywoodite structure, a disordered interlayer region contains approximately one Pb and ten H₂O pfu. In the hanahanite structure, ZnO₄ tetrahedra in adjacent sheets are linked by sharing corners and the interlayer region only contains an H₂O group.