The Getafe rock: Fall, composition and cosmic ray records of an unusual ultrarefractory scoriaceous material

Abstract

In 1994 a moving car and its driver, on a highway in southern Madrid (Getafe), were struck by a falling rock. Eighty-one additional fragments (total weight : 55.926 kg) were later recovered, which all pointed towards a meteorite fall. A study of the composition of this object revealed an ultrarefractory material displaying a most unusual chemical make-up which differs from any known meteorite class, and for some elements and minerals approaches the composition of CAÍ (Ca-Al-rich inclusions in chondrites). A study of some cosmic-ray-produced stable and radioactive nuclides indicates: a) space and terrestrial exposure ages which do not exceed 1,000 and 520,000 years, respectively; b) the presence of a small 22 Ne excess (1,100 °C fraction), which suggests either a nucleogenic contribution from the 19 F(a,n) 2 Ne reaction or a trapped Ne signature distinct from atmospheric Ne, and c) the existence of minor variations in the 3 Ar/ 36 Ar ratios also indicating a nucleogenic component or fractionation effects. 14 C data are consistent with "modern" carbón originated in the period 1955-1958 and not earlier or more recently. The possibility that the Getafe rock could have a man-made origin (i.e. ceramic and refractory tiles, industrial slag) is also considered. Keywords:Getafe rock. FalL Composition. Cosmic ray records. Meteorite. Slag. Madrid. Spain. La roca de Getafe: Caída, composición y registro de rayos cósmicos de un material inusual ultrarrefractario de escoriaResumen En 1994, una roca impactó, en trayectoria descendente, contra un coche que circulaba por la zona sur de Madrid (Getafe), dañando al conductor en el proceso de caída. Posteriormente, se recuperaron otros ochenta y un fragmentos adicionales, con un peso total de 55.926 kg, apuntando todo ello a que se trataba de una típica caída meteorítica. El estudio mineralógico y geoquímico de la roca de Getafe revela que se trata de un material ultrarrefractario, que muestra una composición muy inusual que difiere de los meteoritos conocidos y que, para algunos elementos y minerales, se aproxima a la composición de las CAÍ (inclusiones ricas en Ca-Al en condritas). El estudio de algunos núclidos estables y radiactivos producidos por los rayos cósmicos indica: a) edades de exposición en el espacio y terrestres que no sobrepasan los 1.000 y 520.000 años, respectivamente; b) la presencia de un pequeño exceso de 22

Survival of lichens and bacteria exposed to outer space conditions – Results of the Lithopanspermia experiments

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Analysis and chemical composition of larnite-rich ultrarefractory materials

“…These rocks come from the mineral collection of the "Museo Nacional de Ciencias Naturales" in Madrid. Besides the interest of the singularity of their mineral paragenesis, these larnite-rich rocks are of utmost importance and are labeled, "rocks of possible meteoritical origin", in relation with the well documented 1994 impact in the area of Getafe (a town south of Madrid) [12][13][14]. These materials exhibit a complex assemblage involving native, oxide and silicate minerals (mainly native iron, wustite, larnite).…”

The meteorite collection of the National Museum of Natural Sciences, Madrid, Spain: An updated catalog

“…In 1994 a supposed meteorite fell in the town of Getafe (South Madrid). The studies carried out so far indicate that although the circumstances surrounding the fall are well documented, the petrologic and geochemical characteristics of the material (a Iamite-rich ultrarefractory rock) do not match any of the previously classified meteorites or clearly terrestrial rocks (Martinez-Frias, 1999;Martinez-Frias et al, 1999). It has therefore been included in the catalog as a pseudometeorite.…”