iPhone 14 Pro Max
ƒ/2.2
2.22 mm
1/60
160

It’s mostly Mg-rich diopside (gem-like when backlit) and has zero olivine or plagioclase. The little black blebs scattered throughout are visually striking. They look like random scattered paint dots not aligned along crystal boundaries, or mineral type. Some zoom shots below.

Some thoughts from meteoritic experts:

Tony Irving: “Those subspherical grains are not metal but Fe sulfides (daubreelite alabandite, troilite)”

Andy Tomkins: “Must be melt fractionation to get a diopside dominated rock. Probably cumulate formation to achieve a rock with no plagioclase or olivine. Must be low gravity environment to avoid separation of dense sulfides from silicates. Probably formed deep within an asteroid to achieve the slow crystallisation needed to form big crystals and then exsolution lamellae. Very reduced parent body to get the lack of FeO in the clinipyroxene.”

More research is underway on this material, and we should know its age by the end of August.

49g slice, backlit. 2023 find in Algeria. Met Bull for NWA 15915.

One response to “The Mysterious Ungrouped Achondrite NWA 15915”

  1. Zooming inWithout backlighting Close to terrestrial O-isotope line

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