NWA 11207 – 42.3g

$1,300.00

1 in stock

Category:

Description

CK5-anomalous

42.3g endcut (main mass)
sold with label/certificate of authenticity

The only CK5-anomalous !


It is a dark irregular stone. Cut surface reveals dark interior with mm-sized chondrules. It has a chondritic texture with abundant recrystallized matrix and mm-sized chondrules. Plagioclase average size in the matrix is below 50 μm. Magnetite is the dominant opaque mineral in the matrix and as large euhedral grains up to 100 μm in the chondrules. Sulfide is present as small grains.

Anomalous designation comes from the unusually Fe-poor olivine. Out of 230 equilibrated CK chondrites with available olivine analyses (data from Meteoritical Bulletin Database as of March 2017), only three have similar or lower Fa content : GRA 98102 (CK4, Fa24), NWA 7615 (CK6, 24.7±0.4), NWA 5580 (CK4-an, Fa25.2).

 

Northwest Africa 11207 (NWA 11207)
Western Sahara
Purchased: 2016 May 25

Classification: CK5-an

History: Purchased from Abdeltif Mechaguen

Physical characteristics: A dark irregular stone. Cut surface reveals dark interior with mm-sized chondrules.

Petrography: Chondritic texture with abundant recrystallized matrix and mm-sized chondrules. Plagioclase average size in the matrix is below 50 μm. Magnetite is the dominant opaque mineral in the matrix and as large euhedral grains up to 100 μm in the chondrules. Sulfide is present as small grains.

Geochemistry: Olivine Fa24.9±0.3, NiO 0.43±0.07 wt% (N=6), orthopyroxene Fs23.6Wo0.7 (N=1), plagioclase An24.0Ab72.5Or3.6 (N=2). Magnetite has Cr2O3 2.7±0.3 wt%, Al2O3 1.1±0.6 wt%, NiO 0.17±0.10 wt% (N=3). Magnetic susceptibility log χ (× 10-9 m3/kg) = 4.81.

Classification: CK5-an. Anomalous designation from the unusually Fe-poor olivine. Out of 230 equilibrated CK chondrites with available olivine analyses (data from Meteoritical Bulletin Database as of March 2017), only three have similar or lower Fa content: GRA 98102 (CK4, Fa24), NWA 7615 (CK6, 24.7±0.4), NWA 5580 (CK4-an, Fa25.2).

Specimens: Type specimen and polished sections at CEREGE. Main mass with Pierre-Marie Pelé.