Sunday, June 27, 2021

The Sericho Pallasite Meteorite - XRF Analysis

I obtained 2 fragments of the Sericho Pallasite Meteorite, "discovered" in Habaswein, Eastern Kenya in 2016. 
The meteorite has been known to local populations for many years but it wasn't until 2016 when the meteorite was officially classified as such. This was a huge meteorite - so far 2.8t were recovered.

A highly sculpted complete fragment of the Sericho meteorite. This specimen exhibits the "classic" meteorite look and the fragment is complete, not cut from a larger piece.

The second specimen is an end-cut piece from a larger fragment. It exhibits the typical "fusion crust" from the entry in Earth's atmosphere. 

The back side of the second piece with straight polished cut reveals the pallasite nature of the meteorite and a structure of olivine crystals.

The XRF Analysis setup - the polished cut of the meteorite is exposed to the 59.54 keV X-Ray source and the X-Ray detector. I placed the source a bit further away decreasing the intensity in order to eliminate parasitic peaks coming from Np, Au and Ag in the source itself. The weaker beam resulted in a long acquisition time - nearly 6 hours but produced a fairly clean spectrum.

XRF analysis plot.
As it turns out from an XRF point of view, much like most other meteorites, Sericho is typical and quite boring - no exotic metals are present - just Iron, Nickel and traces of Cobalt and Chromium.
The plot prominently features the Kα1 and Kβ1 peaks of Iron and smaller peaks of Nickel. Cobalt is in very low concentration (0.8%) and masked but if one looks for it, it can be seen in the irregular shape of the base (on the right side) of the Ni Kα1 photopeak. The Ni Kα1 at 7.48 keV is too close to the 7.65 keV of the Kβ1 of Cobalt just at the edge of the detector resolution. The 6.93 keV Kα1 line of the Co is dominated by the Kβ1 Fe at 7.06 keV and can not be differentiated. Chromium can not be detected at all with my setup due to the trace amounts (0.03%)


Anonymous said...

I don't know who you are but you should definitely make a youtube channel. As you may have noticed almost no one reads blogs, but your projects are extremely interesting to a significant amateur community and you will attract vastly more views with video than here. Let me know if you make one because I'll be the first to subscribe. I'm Muonium and I have videos about lasers, fusion, superconductivity and a few other things there.

Andrey E. Stoev said...

Thank you for the encouragement. Honestly, you are not the first one to suggest this but the purpose of my blog is not to attract views (as you can see I have turned off any ads or means to monetize it) - I just log my experiments and activities and whoever needs this information, a simple Google search will bring him/her here.
Youtube channel just doesn't fit my ideas for presenting the information with easy-to-follow yet detailed description. I can see how the crowd is attracted to a 15-20 minute entertaining videos but this just doesn't fit with the way I see things - maybe I am just old fashioned :-)