Plumbogottlobite, PbMg(VO 4 )(OH), the Pb analogue of gottlobite and the Mg analogue of descloizite

Abstract. Plumbogottlobite (IMA 2025-075), PbMg(VO4)(OH), is a new mineral from the Glücksstern mine, Gottlob Hill, Friedrichroda, Gotha District, Thuringia, Germany; it is a late-stage, low-temperature hydrothermal mineral occurring on baryte and hausmannite. Plumbogottlobite forms orange-brown tablets up to about 0.2 mm in diameter. The mineral has a light-orange-brown streak, adamantine lustre, a Mohs hardness of ∼ 4 to 4.5, brittle tenacity, irregular to conchoidal fracture, no cleavage, and a calculated density of 5.359 g cm−3. Optically, plumbogottlobite crystals are biaxial (–), with 2V=84(1)°. The empirical formula from electron probe microanalyses based on 5 O apfu is (Pb0.89□0.11)Σ1.00(Mg0.77Cu0.192+Mn0.092+)Σ1.05(VO4)(OH) (+0.12 H for charge balance). Plumbogottlobite is orthorhombic with space group Pnma and single-crystal unit-cell parameters a=7.6104(7), b=6.1091(6), c=9.3968(8) Å, V=436.88(7) Å3, and Z=4. The crystal structure is refined to R1=0.0302 for 429 reflections with I>2σI. The mineral is the Pb analogue of gottlobite and the Mg analogue of descloizite.