NWA 16734 : Pallasite, Ungrouped

Class:Pallasite, ungrouped

Weathering grade:low

Fayalite (mol%):29.75±0.32 (n=15)

Magnetic suscept.:5.37

Classifier:J. Gattacceca, C. Sadaka, CEREGE

Type spec mass (g):21.2

Type spec location:CEREGE

Main mass:Kuntz

Meteoritical Society Database

Silicate is olivine only, only three pallasite ungrouped are in that case (the others are pyroxene bearing). This is the most more ferroan silicates ever found in a pallasite, and by far ! Main Group Pallasite are about Fa11 to Fa13, Mont Torniat 001 is Fa21.2±0.6, Gyarub Zangbo Fa21.6±0.4... NWA 16734 is Fa29.75±0.32, quite a jump.

Chromite composition is unique amongst pallasites as well.

The olivine, chromite, and oxygen isotopic compositions place this pallasite outside of the Main Group and Eagle Station pallasite groups. It is also different from other ungrouped pallasites registered to date in the Meteoritical Bulletin Database.

O isotope plots NWA16734 vs pallasites.jpg

Source : GYARUB ZANGBO: AN ANOMALOUS CARBONACEOUS PALLASITE. Y. Jiang, X. R. Zhang, W. Z. He, S. Y. Liao, C. Herd, Y. B. Peng, W. B. Hsu - Plot as defined by Jerome Gattacceca (CEREGE)