Pabellóndepicaite, Cu²⁺₂(N₃C₂H₂)₂(NH₃)₂(NO₃)Cl·2H₂O, a new 1,2,4-triazolate mineral from the guano deposit at Pabellón de Pica, Iquique Prov

Abstract The new mineral pabellóndepicaite (IMA2023-104), Cu 2+ 2 (N 3 C 2 H 2 ) 2 (NH 3 ) 2 (NO 3 )Cl·2H 2 O, was found in the guano deposit at Pabellón de Pica, Iquique Province, Chile, where it is a secondary phase formed at the contact between an altered guano deposit and a chalcopyrite-bearing gabbro. Pabellóndepicaite occurs on salammoniac in association with antipinite, bojarite, dittmarite, halite, joanneumite, sampleite, struvite, wheatleyite and whewellite. Crystals are rectangular blades or tablets, up to ∼0.2 mm long, flattened on {001} and elongated along [100] and exhibiting the forms {010}, {001}, {011} and {102}. Crystals are indigo blue and transparent, with vitreous lustre and light indigo blue streak. The mineral is brittle with curved and stepped fracture. The Mohs hardness is ∼2½. Cleavage is perfect on {001} and good on {010}. The density is 1.95(2) g·cm –3 . Optically, pabellóndepicaite is biaxial (+) with α = 1.583(3), β = 1.596(3) and γ = 1.644(3) (white light). The 2V is 56(2)° with distinct r > v dispersion. The optical orientation is X = a , Y = b , Z = c and the pleochroism is X light indigo blue, Y indigo blue, Z pale indigo blue; Y > X > Z . The empirical formula is Cu 2 Cl 1.25 N 9 C 4 H 13.75 O 4.75 (with H, C and N calculated based on the structure). Pabellóndepicaite is orthorhombic, space group Pmma , with cell parameters: a = 7.2118(12), b = 9.0983(15), c = 11.128(3) Å, V = 730.2(2) Å 3 and Z = 2. The structure ( R 1 = 6.65% for 482 I > 2σ I reflections) contains two types of polyhedral chains (1) a zig-zag chain of CuN 4 Cl 2 octahedra linked by sharing Cl atoms and the N–N edges of 1,2,4-triazolate groups and (2) a chain of CuN 4 O 2 octahedra alternating with NO 3 triangles. The chains are linked to one another by 1,2,4-triazolate groups to form layers with isolated H 2 O groups in their cavities.