Alby sur Chéran

Haute Savoie, France

Fell 2002 February

Achondrite (monomict basaltic eucrite)

A 252 g stone with black shiny fusion crust was found on March 22 in the roof of a building, in a hole in the insulating material. Water was first observed leaking from the ceiling inside the building at 8:30 am on March 18, 2002. The stone had broken into 2 fragments (238.9 g and 13 g) upon impact. Taking into account the local amount of rainfall in the previous days, the absorption of water by the porous insulating material and the distance between the hole in the roof and the leak in the ceiling, leads to an estimate that the fall took place between February 3 and February 14. Mineralogy and classification (M. Bourot-Denise, MNHNP): low-Ca pyroxene En₃₆Wo₃ with lamellae of high-Ca pyroxene En_29.5Wo_42.5, and laths of plagioclase An₉₀; consists of clasts with pyroxene grain size about 100-200 µm, in a matrix of same texture and composition but smaller grain size (~50-100 µm). Minor phases include chromite (0.3% MgO, 8% Al₂O₃, 2.6% TiO₂, 0.6% MnO), ilmenite (0.4% MgO, 1% MnO), silica, iron sulfide, Fe-Ni metal. Specimens: type specimen, 130 g, MNHNP; rest of the mass with finder.