Karlditmarite, Cu9O4(PO4)2(SO4)2, the first copper phosphate-sulfate mineral from the Tolbachik volcano, Kamchatka, Russia
Year: 2025
Type: article
Abstract: Karlditmarite (IMA 2021-003), Cu9O4(PO4)2(SO4)2, is a new mineral species from an active Arsenatnaya fumarole, Tolbachik volcano, Kamchatka peninsula, Russia. Karlditmarite occurs as green prismatic crystals. The mineral is biaxial (–), with α = 1.872(2)°, β = 1.835(3)°, and γ = 1.810(3)° (589 nm). Under the microscope, karlditmarite is green with weak pleochroism. Electron microprobe analysis provided the empirical formula (Cu8.614Zn0.175Al0.053Ca0.019Fe0.157)(P1.574S1.814As0.444V0.109Si0.059)O20. Karlditmarite is triclinic, P1¯: a = 6.1256(7) Å, b = 7.9192(8) Å, c = 7.9866(8) Å, α = 75.173(2)°, β = 86.639(2)°, γ = 88.660(2)°, V = 373.87(7) Å3. The crystal structure (R1 = 0.039) is unique. The [Cu9O4∞2]10+ layer in karlditmarite can be described as composed of six-membered rings, in which two of the six OCu4 tetrahedra share a common edge. The interlayer space between the bends of the highly corrugated [Cu9O4∞2]10+ layers hosts phosphate tetrahedra, whereas sulfate tetrahedra are situated above the centers of the rings. Karlditmarite is the first anhydrous Cu phosphate-sulfate mineral among more than 100 copper oxysalt mineral species known from the active fumaroles. In addition, phosphorus geochemistry in fumarolic environments is discussed here.
Source: American Mineralogist
DOI: 10.2138/am-2025-9994
Language: English
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W4415971574