The Meteoritical Bulletin, No. 105
Grarat Zawi, Western Sahara
Find: 15 November 2015
Mass: 108.2 g
characteristics: Total mass of the meteorite = 108.2 g and comprises several pieces,
the larger weighing 80.5 g.
A highland impact-melt breccia with an unusually large amount of
impact-generated glass. Displays multiple generations of melting and
breccia-in-breccia formation. Brown to black devitrified glass swirls
encompass heavily fragmented lithic clasts and mineral fragments. Lithic
clasts represent 40% of the meteorite and have been partially to completely
consumed during multiple impact and melting events. Clasts are heavily
brecciated and range in size from 1.4 to 0.1 mm long. The clasts are
plagioclase-rich with pyroxenes, olivines, spinel, and ilmenite in ophitic
to poikilitic textures. Large broken plagioclase grains and small olivines
and pyroxenes are found within the matrix. Lithic types range from FANs to
Hi-Mg Suite rocks.
Geochemistry: Mineral compositions and
geochemistry: Analyses were obtained from both lithic clasts and lose
mineral fragments from within the breccia matrix. Plagioclase compositions
average An95.7±1.7 (N=43). Average pyroxene composition is Fs36.6±13.3Wo16.4±8.2
(N=73). Average olivine composition is Fs30.9±12.9 (N=50). Fe/Mn
ratios for pyroxenes are 58.7±8.1 (N= 73) and olivines are 98.8±8.7 (N=50).