Kleberite, ideally Fe3+Ti6O11(OH)5, is a new mineral (IMA 2012-023) from Tertiary sands at Königshain, Saxony, northeast Germany. It is also found in heavy mineral sands from the Murray Basin, southeast Australia and at Kalimantan, Indonesia. It occurs as rounded anhedral to euhedral translucent grains, 0.04–0.3 mm across, which are generally red-brown, but grade to orange with decreasing iron content. Associated minerals include ilmenite, pseudorutile, ‘leucoxene’, tourmaline and spinel. The density measured by pycnometry is 3.28 g cm−3, which is lower than the calculated density of 3.91 g cm−3, due to intragrain porosity which is not penetrated by the immersion fluid. The intragrain pores, of median diameter 18 nm, are partially filled with impurity phases including kaolinite, diaspore and quartz. Kleberite grains have a uniaxial (−) character, but localized regions are weakly biaxial (−) with 2V close to zero. The mean refractive index, calculated from reflectance measurements, is 2.16(3). The mean empirical formula from electron-microprobe analyses of 15 Königshain kleberite grains is class="inline-formula" id="inline-formula-1">mg class="math mml" alt="Formula" src="45/embed/mml-math-1.gif" /> Mg0.06Ti6O11.2(OH)4.8[Al0.59Si0.31P0.04O1.60·1.8H2O], where the formula element in square brackets represents impurities in the pores. Kleberite forms over a compositional range with [Ti]/[Fe + Ti] atomic ratios from 0.8–0.9. It has monoclinic symmetry,