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Met Name

Met Type

Thin Sections

4574 grams.   Winonaite

TKW 8.03 kg. Fall not observed. Purchased August 2019, Nouakchott, Mauritania.

MPOD Moderator writes:

Original photo plus 2 copies with different degrees of adjustment. Feedback is appreciated.

 

Albert writes:

The largest winonaite find after Winona. The three stones (4575 g/ 14 cm on display, 2325 g and 1029 g) exhibit a similar physical aspect. About 80% of the surface is wind ablated with prominent metal wedges and depressed silicate clasts. Whenever large metal areas are exposed Widmanstätten pattern is visible as thin shiny taenite bands separating millimetric kamacite with a greenish oxidized surface. Metal edges may be shiny otherwise covered with dark oxide.

The bottom side of the stones are covered with remnants of weathered fusion crust. Poorly shaped regmaglypths are observed in relation with the irregular texture of the rock (metal and troilite filled fractures separating silicate clasts). Fine grained olivine and emerald green pyroxene are observed where the crust is missing. Very fresh, unlike Winona.

According to their oxygen isotopic composition, the silicate part of winonaites derive from a differentiated parent body. Their texture indicates they are breccias with a metal matrix derived from a large parent body.

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