FORMATION OF CARBONATES IN THE TATAHOUINE METEORITE

The Tatahouine meteorite, in southern Tunisia, shows terrestrial conta mination that developed during 63 years of exposure on Earth's surface . Samples collected on the day of the fall in 1931 contained fractures , with no secondary minerals, whereas samples collected in 1994 contai n calcite aggregates (70 to 150 micrometers) and rod-shaped forms (100 to 600 nanometers in length and 70 to 80 nanometers in diameter) on t he fractures. Carbon isotope analysis of the carbonates within the Tat ahouine meteorite [delta(13)C = -2.0 per mil Pee Dee belemnite standar d (PDB)] and the underlying ground (delta(13)C = -3.2 per mil PDB) con firm their terrestrial origin.