Výskyt whewellitu v pelosideritoch uhoľného ložiska Handlová (Slovenská republika)
Martin Števko, Peter Bačík, Peter Cagáň
Whewellite was identified on fissures in central part of pelosiderite concretions and lenses at the Handlová coal deposit. It forms colourless to white crystalline aggregates together with vitreous lustre associated together with crystalline aggregates of quartz and fine-grained pyrite. Rarely well developed tabular to prismatic crystals (up to 1 cm) are present. Whewellite shows intense green-yellow fluorescence and phosphorescence in long-wave UV light. The unitcell parameters of whewellite refined from powder X-ray data are: a = 6.2925(6) Å, b = 14.5947(10) Å, c = 10.1230(2) Å, β = 109.446(8)° and V = 876.64(5) Å3. An infrared spectrum of whewellite from Handlová is given. The bands of oxalate groups as well as molecular H2O were identified. Whewellite was formed as youngest phase in reductive environment with high activity of Ca2+ ions. Oxalic acid was formed by decomposition of organic matter.