Today I’m happy to share NMM 4006, a glass (V-type) micrometeorite measuring approximately 0.3 mm with a large empty imprint on the top where a metal bead has fallen out. Though somewhat tragic, this loss has provided us with a unique opportunity, as it means we can see the bottom of the hole, which would not be visible if the micrometeorite were intact.

So let’s take advantage of the scenario and discuss!

Within the hole, we can see that the coarse olivine crystals in the bottom are surrounded by an iron sulfide rim and a narrow crystalline band. Note the texture of these materials. I wonder what inferences can be made about the formation of the bead and surrounding crystals?

Opposite, in the back of the oriented micrometeorite is a large open vesicle that formed when gas volatiles escaped during entry. The matrix of the glass spherule is dark olive green/brown with a peculiar surface pattern. To be honest, I am not sure what may have caused these strange abrasions. It looks almost like a thin “film” with lots of scratches on the surface is.

Do you have any suggestions?

When I asked this question on the Project Stardust Facebook Page, Mark Waterbury hypothesized that perhaps these scratches formed because of physiochemical forces, pushing material up to the surface layer, which could have lower free energy. Daniel Thommen (who discovered and kindly gifted NMM 3162 to me) suggested that the scratches are likely due to mechanical damage inflicted by harder particles on Earth. Jesus Cejas wondered if the scratches could be the expression of a different compound in the glass matrix that appeared during melting at a high temperature.

What fantastic ideas! I feel truly grateful for the wonderful community of people on social media who share my curiosity and fascination with micrometeorites!

Jan Braly Kihle and I recently began a new research project with the brilliant astrophysicist Dr. Roar Skartlien from the Institute for Energy Technology (IFE). We will be investigating how different variables like entry speed, temperature, entry mass, and entry angle affect the formation of micrometeorites.

I’ll be sure to share updates on our project here and on social media.

As always, thank you for taking the time to be here today and please reach out on Facebook, Instagram, and Twitter with your questions and comments!

Yours truly,

Jon Larsen