A Lagerstätte from Australia provides insight into the nature of Miocene mesic ecosystems.

Reduced precipitation in the Miocene triggered the geographic contraction of rainforest ecosystems around the world. In Australia, this change was particularly pronounced; mesic rainforest ecosystems that once dominated the landscape transformed into the shrublands, grasslands, and deserts of today. A lack of well-preserved fossils has made it difficult to understand the nature of Australian ecosystems before the aridification. Here, we report on an exceptionally well-preserved rainforest biota from New South Wales, Australia. This Konservat-Lagerstätte hosts a rich diversity of microfossils, plants, insects, spiders, and vertebrate remains preserved in goethite. We document evidence for several species interactions including predation, parasitism, and pollination. The fossils are indicative of an oxbow lake in a mesic rainforest and suggest that rainforest distributions have shifted since the Miocene. The variety of fossils preserved, together with high fidelity of preservation, allows for unprecedented insights into the mesic ecosystems that dominated Australia during the Miocene.

Quiescent Mineralisation for Free-standing Mineral Microfilms with a Hybrid Structure.

HYPOTHESIS: The air-solution interface of supersaturated calcium hydrogen carbonate (Ca(HCO3)2) represents the highest saturation state due to evaporation/CO2-degassing, where calcite crystals are expected to nucleate and grow along the interface. Hence, it should be possible to form a free-standing mineral-only calcium carbonate (CaCO3) microfilm at the air-solution interface of Ca(HCO3)2. The air-solution interface of phosphate buffered saline (PBS) could represent a phase boundary to introduce a hybrid microstructure of CaCO3 and carbonate-rich dicalcium hydroxide phosphate (carbonate-rich hydroxylapatite). EXPERIMENTS: Supersaturated Ca(HCO3)2 was prepared at high pressure and heated to form CaCO3 microfilms, which were converted to bone-like microfilms at the air-solution interface of PBS by dissolution-recrystallisation. The microfilms were characterised by scanning electron microscopy, 3D confocal microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, laser Raman microspectroscopy, and X-ray photoelectron spectroscopy. An in situ X-ray diffraction (XRD) system that simulates the aforementioned interfacial techniques was developed to elucidate the microfilms formation mechanisms. FINDINGS: The CaCO3 and bone-like microfilms were free-standing, contiguous, and crystalline. The bone-like microfilms exhibited a hybrid structure consisting of a surface layer of remnant calcite and a carbonate-rich hydroxylapatite core of plates. The present work shows that the air-solution interface can be used to introduce hybrid microstructures to mineral microfilms.

A vibrational spectroscopic study of philipsbornite PbAl3(AsO4)2(OH)5.H2O-molecular structural implications and relationship to the crandallite subgroup arsenates.

The presence of arsenic in the environment is a hazard. The accumulation of arsenate by a range of cations in the formation of minerals provides a mechanism for the remediation of arsenate contamination. The formation of the crandallite group of minerals provides a mechanism for arsenate accumulation. Among the crandallite minerals are philipsbornite, arsenocrandallite and arsenogoyazite. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of philipsbornite to be studied. The Raman spectrum of philipsbornite displays an intense band at around 840 cm(-1) attributed to the overlap of the symmetric and antisymmetric stretching modes. Raman bands observed at 325, 336, 347, 357, 376 and 399 cm(-1) are assigned to the ν(2) (AsO(4))(3-) symmetric bending vibration (E) and to the ν(4) bending vibration (F(2)). The observation of multiple bending modes supports the concept of a reduction in symmetry of the arsenate anion in philipsbornite. Evidence for phosphate in the mineral is provided. By using an empirical formula, hydrogen bond distances for the OH units in philipsbornite of 2.8648 Å, 2.7864 Å, 2.6896 Å cm(-1) and 2.6220 were calculated.

Identification of montgomeryite mineral [Ca4MgAl4(PO4)6·(OH)4·12H2O] found in the Jenolan Caves-Australia.

In this paper, we report on many phosphate containing natural minerals found in the Jenolan Caves - Australia. Such minerals are formed by the reaction of bat guano and clays from the caves. Among these cave minerals is the montgomeryite mineral [Ca(4)MgAl(4)(PO(4))(6)·(OH)(4)·12H(2)O]. The presence of montgomeryite in deposits of the Jenolan Caves - Australia has been identified by X-ray diffraction (XRD). Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the crystal structure of montgomeryite. The Raman spectrum of a standard montgomeryite mineral is identical to that of the Jenolan Caves sample. Bands are assigned to H(2)PO(4)(-), OH and NH stretching vibrations. By using a combination of XRD and Raman spectroscopy, the existence of montgomeryite in the Jenolan Caves - Australia has been proven. A mechanism for the formation of montgomeryite is proposed.

Raman spectroscopic study of the mineral arsenogorceixite BaAl3AsO3(OH)(AsO4,PO4)(OH,F)6.

Arsenogorceixite BaAl(3)AsO(3)(OH)(AsO(4),PO(4))(OH,F)(6) belongs to the crandallite mineral subgroup of the alunite supergroup. Arsenogorceixite forms a continuous series of solid solutions with related minerals including gorceixite, goyazite, arsenogoyazite, plumbogummite and philipsbornite. Two minerals from (a) Germany and (b) from Ashburton Downs, Australia were analysed by Raman spectroscopy. The spectra show some commonality but the intensities of the peaks vary. Sharp intense Raman bands for the German sample, are observed at 972 and 814 cm(-1) attributed to the ν(1) PO(4)(3-) and AsO(4)(3-) symmetric stretching modes. Raman bands at 1014, 1057, 1148 and 1160 cm(-1) are attributed to the ν(1) PO(2) symmetric stretching mode and ν(3) PO(4)(3-) antisymmetric stretching vibrations. Raman bands at 764 and 776 cm(-1) and 758 and 756 cm(-1) are assigned to the ν(3) AsO(4)(3-) antisymmetric stretching vibrations. For the Australian mineral, the ν(1) PO(4)(3-) band is found at 973 cm(-1). The intensity of the arsenate bands observed at 814, 838 and 870 cm(-1) is greatly enhanced. Two low intensity Raman bands at 1307 and 1332 cm(-1) are assigned to hydroxyl deformation modes. The intense Raman band at 441 cm(-1) with a shoulder at 462 cm(-1) is assigned to the ν(2) PO(4)(3-) bending mode. Raman bands at 318 and 340 cm(-1) are attributed to the (AsO(4))(3-)ν(2) bending. The broad band centred at 3301 cm(-1) is assigned to water stretching vibrations and the sharper peak at 3473 cm(-1) is assigned to the OH stretching vibrations. The observation of strong water stretching vibrations brings into question the actual formula of arsenogorceixite. It is proposed the formula is better written as BaAl(3)AsO(3)(OH)(AsO(4),PO(4))(OH,F)(6)·xH(2)O. The observation of both phosphate and arsenate bands provides a clear example of solid solution formation.

Vibrational spectroscopy of synthetic stercorite H(NH4)Na(PO4)·4H2O--a comparison with the natural cave mineral.

In order to mimic the chemical reactions in cave systems, the analogue of the mineral stercorite H(NH(4))Na(PO(4))·4H(2)O has been synthesised. X-ray diffraction of the stercorite analogue matches the stercorite reference pattern. A comparison is made with the vibrational spectra of synthetic stercorite analogue and the natural Cave mineral. The mineral in nature is formed by the reaction of bat guano chemicals on calcite substrates. A single Raman band at 920 cm(-1) (Cave) and 922 cm(-1) (synthesised) defines the presence of hydrogen phosphate in the mineral. In the synthetic stercorite analogue, additional bands are observed and are attributed to the dihydrogen and phosphate anions. The vibrational spectra of synthetic stercorite only partly match that of the natural stercorite. It is suggested that natural stercorite is more pure than that of synthesised stercorite. Antisymmetric stretching bands are observed in the infrared spectrum at 1052, 1097, 1135 and 1173 cm(-1). Raman spectroscopy shows the stercorite mineral is based upon the hydrogen phosphate anion and not the phosphate anion. Raman and infrared bands are found and assigned to PO(4)(3-), H(2)O, OH and NH stretching vibrations. Raman spectroscopy shows the synthetic analogue is similar to the natural mineral. A mechanism for the formation of stercorite is provided.

Vibrational spectroscopic analysis of taranakite (K,NH4)Al3(PO4)3(OH)·9(H2O) from the Jenolan Caves, Australia.

Many phosphate containing minerals are found in the Jenolan Caves. Such minerals are formed by the reaction of bat guano and clays from the caves. Among these cave minerals is the mineral taranakite (K,NH(4))Al(3)(PO(4))(3)(OH)·9(H(2)O) which has been identified by X-ray diffraction. Jenolan Caves taranakite has been characterised by Raman spectroscopy. Raman and infrared bands are assigned to H(2)PO(4), OH and NH stretching vibrations. By using a combination of XRD and Raman spectroscopy, the existence of taranakite in the caves has been proven.

Vibrational spectroscopic analysis of the mineral crandallite CaAl3(PO4)2(OH)5·(H2O) from the Jenolan Caves, Australia.

The mineral crandallite CaAl(3)(PO(4))(2)(OH)(5)·(H(2)O) has been identified in deposits found in the Jenolan Caves, New South Wales, Australia by using a combination of X-ray diffraction and Raman spectroscopic techniques. A comparison is made between the vibrational spectra of crandallite found in the Jenolan Caves and a standard crandallite. Raman and infrared bands are assigned to PO(4)(3-) and HPO(4)(2-) stretching and bending modes. The predominant features are the internal vibrations of the PO(4)(3-) and HPO(4)(2-) groups. A mechanism for the formation of crandallite is presented and the conditions for the formation are elucidated.

Raman spectroscopy of newberyite Mg(PO3OH)·3H2O: a cave mineral.

Newberyite Mg(PO3OH)·3H2O is a mineral found in caves such as from Moorba Cave, Jurien Bay, Western Australia, the Skipton Lava Tubes (SW of Ballarat, Victoria, Australia) and in the Petrogale Cave (Madura, Eucla, Western Australia). Because these minerals contain oxyanions, hydroxyl units and water, the minerals lend themselves to spectroscopic analysis. Raman spectroscopy can investigate the complex paragenetic relationships existing between a number of 'cave' minerals. The intense sharp band at 982 cm(-1) is assigned to the PO4(3-)ν1 symmetric stretching mode. Low intensity Raman bands at 1152, 1263 and 1277 cm(-1) are assigned to the PO4(3-)ν3 antisymmetric stretching vibrations. Raman bands at 497 and 552 cm(-1) are attributed to the PO4(3-)ν4 bending modes. An intense Raman band for newberyite at 398 cm(-1) with a shoulder band at 413 cm(-1) is assigned to the PO4(3-)ν2 bending modes. The values for the OH stretching vibrations provide hydrogen bond distances of 2.728 Å (3267 cm(-1)), 2.781 Å (3374 cm(-1)), 2.868 Å (3479 cm(-1)), and 2.918 Å (3515 cm(-1)). Such hydrogen bond distances are typical of secondary minerals. Estimates of the hydrogen-bond distances have been made from the position of the OH stretching vibrations and show a wide range in both strong and weak bonds.