Northwest Africa 1240

Northwest Africa

Found 2001

Achondrite (eucrite, anomalous)

A single stone of 98 g was bought in Zagora in 2001 November. Classification and mineralogy (J-A. Barrat, UAng; A. Jambon, UPVI; M. Bohn, I-CB; V. Sautter, MNHNP; Ph. Gillet, ENSL; Ch. Göpel, IPGP; F. Keller, LGCA): the meteorite has the texture of an unbrecciated achondrite consisting of skeletal low-Ca pyroxene phenocrysts in a variolitic (fan-spherulitic) mesostasis of pyroxenes, plagioclase, and accessory skeletal chromite, iron, silica, fayalite, troilite and phosphate. The rock resembles some Apollo 15 pigeonite basalts but mineral and bulk rock compositions indicate a relationship to eucrites. Pyroxenes (FeO/MnO molar = 31, n = 540) are unequilibrated and comprise a compositional range wider than in any other HED meteorite with phenocryst cores, En76Fs22.1Wo1.9, and mesostasis pyroxenes (pyroxferroite?), En0.3Fs83.4Wo16.3; plagioclase, An90.9 (n = 122), range, An88 to An92. Bulk composition: Mg-rich Kapoeta-like clasts; slightly depleted in light REEs similar to the cumulate eucrite Moore County; possibly an impact-melted cumulate eucrite. Specimens: type specimen, 17 g and one polished thin section, ENSL; main mass is with the anonymous purchaser.