Tomasz Krzykawski

Rusinovite, Ca10(Si2O7)3Cl2: a new skarn mineral from the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia

Rusinovite, Ca 10 (Si 2 O 7 ) 3 Cl 2 , was discovered in an altered carbonate-silicate xenolith enclosed in ignimbrites of the Upper Chegem volcanic caldera. The mineral is named after Vladimir Leonidovich Rusinov (1935–2007), a Russian petrologist and expert in the field of thermodynamics of non-equilibrium mineral systems. A synthetic analogue of rusinovite is also known. The new mineral has an OD structure of which only the average structure could be determined based on strong and sharp reflections recorded by single-crystal X-ray diffraction: space group Cmcm , a = 3.7617(2), b = 16.9385(8), c = 17.3196(9) A, V = 1103.56(10) A 3 , Z = 2. The average structure ( R 1 = 3.18 %) is characterized by columns of face-sharing disilicate units extending parallel to a . However, in the true structure only each second (Si 2 O 7 ) unit is occupied. Although rusinovite has a stoichiometry similar to the apatite-group mineral nasonite, Pb 6 Ca 4 (Si 2 O 7 ) 3 Cl 2 , the two structures are considerably different. Rusinovite has following optical properties: α = 1.645(2), β = 1.664(2), γ = 1.675(3); Δ = 0.030, 2V meas = −75(10) °; 2V calc = −74.6 °; the Mohs hardness is 4–5, the density is 2.91 g/cm 3 . The mineral forms fibrous crystals often intergrown into spherolites and displays good cleavage parallel to (010). The Raman spectrum of rusinovite strongly resembles that of another skarn calcium-disilicate: rankinite, Ca 3 Si 2 O 7 .

Anti-predator adaptations in a great scallop (Pecten maximus) – a palaeontological perspective

Abstract Shelly fauna was exposed to increased pressure exerted by shell-crushing durophagous predators during the so-called Mesozoic Marine Revolution that was initiated in the Triassic. As a result of evolutionary ‘arms race’, prey animals such as bivalves, developed many adaptations to reduce predation pressure (e.g. they changed lifestyle and shell morphology in order to increase their mechanical strength). For instance, it was suggested that Pectinidae had acquired the ability to actively swim to avoid predator attack during the early Mesozoic. However, pectinids are also know to have a specific shell microstructure that may effectively protect them against predators. For instance, we highlight that the shells of some recent pectinid species (e.g. Pecten maximus) that display cross-lamellar structures in the middle part playing a significant role in the energy dissipation, improve the mechanical strength. In contrast, the outer layers of these bivalves are highly porous, which allow them to swim more efficiently by reducing the shell weight. Pectinids are thus perfect examples of animals optimising their skeletons for several functions. We suggest that such an optimisation of their skeletons for multiple functions likely occurred as a results of increased predation pressure during the so-called Mesozoic Marine Revolution.

Orthorhombic 11C pyrrhotite from Michałkowa, Góry Sowie Block, The Sudetes, Poland – preliminary report

Abstract This study provides the preliminary report about first occurrence of orthorhombic 11C pyrrhotite (Fe(1-x)S) from the Sudetes, Poland. Samples of pyrrhotite-containing two-pyroxene gabbro were found in a classic pegmatite locality in Michałkowa near Walim in the Góry Sowie Block. Based on microscopic methods, pyrrhotite is associated with pentlandite, chalcopyrite, chromite, ilmenite, gersdorffite, magnetite, biotite, magnesiohornblende, clinochlore, lizardite and talc. X-Ray diffraction (XRD) indicate that pyrrhotite has orthorhombic 11C structure and it is characterized by: a = 3.433(9) Å, b = 5.99(2) Å, c = 5.7432(5) Å, β = 90º and d102 = 2.06906 Å. Mössbauer studies confirmed the XRD data. Pyrrhotite has three sextets with hyperfine parameter values 30.8 T for sextet A, 27.9 T and 25.8 T for sextets B and C respectively, indicating orthorhombic structure, the composition near Fe10S11 and x = 0.0909

Mechanism of Rhabdophane-(La) And Lanthanite-(La) Formation during Reduction of Bioavailabe Nutrients in Water based on SEM and XRD Study

Abstract This study presents results of SEM and XRD investigation of products formed after La-rich bentonite application into water containing PO43- and CO32- ions. The main product of the investigated reaction with phosphate and carbonate anions is rabdophane-(La) and lanthanite-(La), respectively. Studied material has adaptation in many water reservoirs only for phosphorus ions reduction. Further studies might find application in case of reduction others hazardous ions. They could be precipitated in the same fast and effective way, to other stable, nontoxic mineral phases. Abstrakt Niniejszy artykuł traktuje o możliwości redukcji nutrientów (np. PO43-, CO32-) za pomocą bentonitu wzbogaconego w lantan. Jak dotąd jedynym zastosowaniem wspomnianego bentonitu jest redukcja jonów fosfonowych w środowiskach wodnych (np. jeziora, rzeki, zastoiska) do stabilnego i nietoksycznego związku mineralnego jakim jest rabdofan-(La). Na podstawie analiz SEM oraz XRD wykazano, że badany materiał umożliwia również redukcję jonów węglanowych do stabilnej i nietoksycznej fazy mineralnej-węglanowej (lantanit-(La)). Dalsze studia nad bentonitem lantanowym, poczynione względem innych, niepożądanych jonów (np. jonów azotanowych czy arsenianowych) mogą przynieść odpowiedzi względem ewentualnego i dalszego, środowiskowego zastosowania bentonitu lantanowego.