Dar al Gani 1023

Libya

Found 1999 summer

Achondrite (ureilite, polymict)

A stone of 149 g was found by an anonymous collector in the Dar al Gani desert. Mineralogy and classification (H. Takeda, Chiba; T. Ishii and M. Ohtsuki, UTok): fragmental breccia, with lithic and mineral clasts embedded in a cataclastic matrix of predominantly ureilitic material. Lithic clasts and fragments include mafic ureilitic material (olivine 86 vol% and pyroxene 12 vol%), Na-rich plagioclase fragments and rare subrounded, dark brown Na-, K-rich glassy grain (SiO2 68 wt%, Al2O3 13.6 wt%, MgO 5.6 wt%, CaO 5.3 wt%, Na2O 6.3 wt%, K2O 0.8 wt%). The pyroxene composition ranges from En79Wo6 to En62Wo4 and En59Wo31; olivine composition ranges from Fo90 to Fo75. The plagioclase composition ranges from An13Ab85 to An33Ab62. A slice of a lithic clast of 3.7 × 2.7 cm in size (sub-sample ,02; 6.89 g slice), is one of the most heavily shocked ureilites known. All mafic silicates are converted into very fine grained materials with a granoblastic texture; carbonaceous vein materials are lost from many grain boundaries; glassy shock-vein materials are observed at some parts of the thin section. Olivine (80 vol%) is more abundant than pyroxene (20%). Pyroxene composition ranges from En86Wo2 to En77Wo10 and En69Wo6; olivine composition ranges from Fo96 to Fo66. The stone is weathered, with a brownish color in hand specimen, but in thin section the weathering grade appears to be very low. Specimens: type specimen, 20.75 g (including sample, 02), NSMT, one thin section, Chiba; main mass with anonymous finder.