I bought a small Tektite at a rock shop a few weeks ago.? I am not a rock collector, but I had read about Tektites and this one intrigued me because it was so darkly colored.? The rock shop had a drawer of them labeled “China Tektites”.? It weighs about 10g, SG of 2.4.? It is very slightly radioactive (detectable with scaler and pancake, but not by ear).
?
Doing a little research, I believe it is an Indochinite based on its appearance and the fact they are very common, and many similar ones are for sale on ebay.? Apparently, people have been pulling them out of their farm fields and rice paddies for years in S. China and Vietnam.? They pile them up to be sold to brokers, and then resold to rock shops, and finally to crazy people.
?
Indochinites are one of a variety of Tektites associated with the largest and youngest Tektite strewnfield on Earth, the Australasian Strewnfield.? According to Wikipedia, it covers 10 to 30% of the Earth’s surface and has been dated to 788,000 years ago.?? Despite the relative youth and large size of this strewnfield, the location of the source crater has not yet been found.? This makes it a bit of a mystery among those in this scientific specialty.
?
Metallic Iron is rarely found in surface or crustal rocks, if you do find some, it is usually some man-made artifact.? If it is an Fe/Ni metal alloy (in the range of 5-25% Ni), you have found an iron meteorite.? If it is a stone containing Fe/Ni metal spheroids (chondrules) it is a Chondritic meteorite.?
?
Tektites are formed from local material that is melted and blasted into the upper atmosphere by a meteorite impact.? Any meteoric material will be greatly diluted by the terrestrial material in the blast melt.? Some Australasian Tektites are known to be relatively Nickel rich (.04%), but it has been a subject of debate whether this Ni content has a significant chrondritic (extraterrestrial) origin or not.? Some of the links (abstracts only) below take one side or the other of the argument. ??I was curious about this.? The Ni component is much lower, probably about 2 orders of magnitude, from my earlier XRF work with Iron meteorites.? I was concerned about Ni interference from my Am241 buttons with my set-up.? So, I asked Charles Young if he would run XRF on the Tektite to see if any Ni could be detected.
?
Charles did find both Fe and Ni, and the ratio looks very similar to scans of iron meteorites that I did a few years back.? However, if the experts can’t decide if such Ni is from here or there, I am unlikely to prove it one way or the other.?
Comment? Suggestions? Any ideas how we to pursue this further?
?
?
