The purpose of this article is to post the above image, here on the Internet, and to continue an on-going discussion about possible pairings of the Dutch Flat meteorite with other irons, based upon this image.

Over the past few years the Dutch Flat meteorite, an iron find from Arizona, has been mentioned often whenever there are discussions about the numerous small irons being found within the strewn field of the Franconia meteorite. But, in a recent article in GCA by John Wasson, it was suggested by the authors that, based upon similar trace element composition (namely, low-Iridium content) the Dutch Flat should be considered as paired to Sikhote-Alin.

It is my opinion, as well as the opinion of several others who have seen the above image, that this iron is far too weathered to be paired to the fall of the Sikhote-Alin meteorite. For the same reason, Dutch Flat does not look like a good pairing with the numerous small irons being found within the Franconia strewn field. But, regardless of any perceived difference in weathering grade, one of the larger specimens of these "Franconia irons" was recently classified and the results confirm its chondritic origin (personal communication with finder).

If the terrestrial age of the Dutch Flat iron were to be measured, it could be conclusive evidence in determining whether it is paired/unpaird to the Sikhote-Alin iron, which fell just 60 years ago this past February. Admittedly, the degree of weathering grade is no indicator of terrestrial age. But experts in the weathering of meteorites can tell the difference between an iron oxide rust that formed after 60 years of exposure in a tundra, versus a magnetite-rich patina on a rind which developed over a much longer period of time in a hot desert. In fact, during my recent conversation with John Wasson, he stated that, "if it can be shown that the exterior of the Dutch Flat iron formed in a desert environment, and was of sufficient age, then it would clearly indicate that it isn't paired to the Sikhote-Alin iron."

So, in a manner of speaking, this article is a "want-ad" seeking just such an expert in terrestrial age-determination of weathered iron meteorites. The candidate expert could benefit from this exercise by having the opportunity to author a paper that alternatively, either confirms that Dutch Flat is paired to Sikhote-Alin, or that Dutch Flat, like the Ainsworth iron, fell before the Sikhote-Alin iron, and is another low-Iridium IIAB, yet all three are unpaired!

Post script:

"I think the comparative trace element analysis for Ainsworth, Sikhote-Alin, and Dutch Flat 
is interesting because the data suggest that Ainsworth and Sikhote-Alin are more alike 
than Dutch Flat is to either of them.  (See the attached spreadsheet I created a few months back 
based on the Dutch Flat data in Meteoritical Bulletin #88 versus corresponding Sikhote-Alin and
Ainsworth data kindly provided by Dr. Wasson.)  One does have to be mindful that, 
for a variety of reasons, measurement uncertainty and/or compositional variability on some elements 
can be 10-15%, so not all differences are statistically significant.  The key difference here is iridium, 
where Dutch Flat is a slight outlier."

References:

Google Web Search

Results 1 - 2 of about 6 for Dutch Flat . (0.09 seconds)

Meteoritical Bulletin: Entry for Dutch Flat