h i g h l i g h t sWe have analysed the mineral sturmanite. Formula Ca 6 (Fe, Al, Mn) 2 (SO 4 ) 2 (B(OH) 4 )(OH) 12 Á26H 2 O. The mineral is unusual as it contains both sulphate and hydroxyborate anions. Chemical analysis shows a homogeneous phase, composed by Ca, Fe, Mn, S, Al and Si. Bands attributed to sulphate and hydroxyborate anions are identified.

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Abstract-The Serra da Cangalha crater structure in northeast Brazil, ∼13 km in diameter, has long been widely considered to be a confirmed impact structure, based on reports of shatter cone findings.Only very limited field work has been carried out at this crater structure. Landsat Thematic Mapper (TM) and Shuttle Radar Topography Mission (SRTM) data sets for the region around this crater structure are compared here with regard to their suitability to determine first-order structural detail of impact crater structures. The SRTM data provide very detailed information regarding drainage patterns and topography. A pronounced central ring of up to 300 m elevation above the surrounding area, two comparatively subdued intermediate rings of 6 and 10.5 km diameter, respectively, and the broad, complex crater rim of up to >100 m elevation can be distinguished in the Serra da Cangalha data. The maximum cratering-related regional deformation (radial and concentric features) seems to be limited to a radial distance of 16-18 km from the center of the structure. A first comparison of macrostructural information from several impact structures with that from Serra da Cangalha does not yield firm trends, but the database is still very small at this stage. The varied nature of the target geology strongly influences the development of structural features in any impact event.