Gilmarit, triklinický Cu3(AsO4)(OH)3, z Bělovsi u Náchoda - první výskyt v České republice.

A very rare mineral gilmarite, triclinic Cu3(AsO4)(OH)3 mineral phase dimorphous with clinoclase, was found in an old abandoned Jirásek granodiorite quarry in Běloves near Náchod, East Bohemia. This is the first occurrence of this mineral in the Czech Republic. Gilmarite occurs there as greenish blue flattened and elongated crystals forming rosettes and crystalline aggregates up to 1 mm in size in association with malachite, olivenite, cuprite and bluish green copper silicate (chrysocolla). Gilmarite is triclinic, space group P1, the unit-cell parameters refined from X-ray powder diffraction data are: a 5.449(2), b 5.870(4), c 5.109(3)Å, α 115.00(3)˚, β 93.09(5)˚, γ 91.83(5)˚ and V 147.6(1) Å3. Chemical analyses of gilmarite correspond to the empirical formula (Cu)2.99[(AsO4)0.98 (PO4)0.01]Σ0.99(OH)2.98 on the basis of As+P+Si+V = 1 apfu. [ABSTRACT FROM AUTHOR]