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.
(S. Roberts, UTenn)
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).