XRD of true suspended glacial mineral dust from Morteratsch Glacier meltwater (June 2025), isolated by centrifugation and filtration

This dataset consists of the mineralogical fingerprint of suspended mineral dust isolated from 500 mL of Morteratsch Glacier meltwater (June 2025). The sample was centrifuged and filtered to concentrate the very fine suspended fraction (glacial flour), which was 7 months later prepared on a silicon wafer and characterized by X-ray diffraction (23 January 2026). The dominant crystalline phases are quartz and feldspar, as expected from granitoid/gnessic bedrock comminution. This dataset represents a high-purity reference of physically entrained glacial dust in meltwater and can serve as a benchmark for aeolian/proglacial fine particulate studies. XRD summary – Morteratsch glacier meltwater filtrate (June 2025) X-ray diffraction of the solid material obtained by sedimentation, centrifugation and filtration of Morteratsch glacier meltwater shows a polyphase, fine-grained silicate assemblage dominated by sheet silicates. The diffractogram exhibits two characteristic basal reflections at d ≈ 10 Å (2θ ≈ 8.9° Cu Kα) and d ≈ 7 Å (2θ ≈ 12.6° Cu Kα), which are diagnostic of illite/muscovite (mica group) and chlorite, respectively. These phases are typical products of mechanical exfoliation of gneisses and mica-rich schists in the Bernina massif drained by the Morteratsch glacier. Numerous weaker reflections between 20° and 35° 2θ indicate the presence of finely dispersed quartz and feldspar, consistent with glacial comminution of crystalline silicate bedrock. The elevated and smoothly decaying background at low angles reflects the nanocrystalline and platy nature of the mineral fraction. No dominant reflections attributable to carbonate minerals or fibrous hazardous phases were detected in the measured angular range. The mineralogical composition therefore corresponds to a micaceous, high-surface-area glacial rock flour derived from Bernina crystalline rocks and carried in colloidal form by the meltwater. Photo from water collection site was recorded 27 August 2019. Water was collected in 2025. pH of filtrate water was pH=5.5.