Takysie Lake
- The Classic "Pseudometeorite" - Found By Harvey H. Nininger - Still a Mystery?
The first time I saw a specimen of Takysie Lake was 16 years ago (in 2000). I had purchased a small stone from an old collector from San Diego. He explained that it was self-collected in 1991 from the "strewn-field" as described by Nininger (and Gary I. Huss) in their 1967 paper
"The Takysie Lake, B. C., Stones: Meteorites or Moon Rock?"
Although this specimen wasn't actually handled by Harvey Nininger, I was still intrigued by this stone. It was clear to me that this stone was a volcanic breccia (exactly as Nininger and Huss had described), but it wasn't obvious to me why Harvey was so convinced that this was a meteorite. So, I took it upon myself to dig deeper into the history of this Nininger find and how it came to be classified as a "pseudometeorite".
The first place I turned to was the on-line Database for the Meteoritical Bulletin (MBD), published by the Meteoritical Society, and searched for the entry for "Takysie Lake". The first thing I noticed was the word "Pseudo" under the column for "Status". The MBD defines "Pseudo" as, "indicates that the name refers to an object that has been proven NOT to be a meteorite". But here lies the problem. There was no reference as to how it was "proven to be NOT a meteorite". The only reference given was the original Nininger& Huss 1967 paper. That same MBD entry used the word "Pseudometeorite" under the column "Type" (or classification). The MBD defines "Pseudometeorite" as, "the recommended classification for an object that has been claimed to be a meteorite, but which is non-meteoritic in origin."
Apparently, Pseudometeorites are "meteor-wrongs" (although that term is not officially-recognized in the MBD). But, not all meteor-wrongs are Pseudometeorites. It appears that Pseudometeorites are a special class of meteor-wrongs. So special that they required actual analysis to be proven that they are NOT (as they were claimed to be) a meteorite. There are only seventy (70) formally-recognized Pseudometeorites in the MBD.
As it turned-out, there wasn't a lot in the literature about the Takysie Lake stones outside of what was written by Huss and by Nininger. So, let's turn to the 1967 paper that first introduced these stones to meteoriticists. Here are the author's exact words:
[Reproduced from: Meteoritics, Vol 3-4, pg169, 1967]
The Takysie Lake stones were found on glacial deposits in British Columbia. They contained neither nickel nor chondrules but they did bear a true fusion crust. Their only other claims to meteoritic origin were 1) their total lack of resemblance to the glacial deposit on which they were found, 2) their evidence of rapid weathering where the fusion crust had been broken, 3) their limited distribution which was consistent with that of known aerolite showers, and 4) all of the 55 recovered stoned were of irregular form, without sharp edges or corners, yet bearing no evidence of the abrasive shaping common to the glacial conglomeration of materials with which they were associated.
Soon after being published, questions were raised about each of the above four (4) "claims":
1) Yes, the stones did not resemble any of the clasts in the till of the underlying glacial deposits, but how similar were these "erratic" stones to the local outcrops of andesitic rock?
2) Yes, the evidence of rapid weathering is dependent upon the age of the fusion crust, but exactly how old is the fusion crust? The fusion crust was subsequently found to be devitrified to palagonite. How long does it take for fusion crust to devitrify?
3) Yes, the distribution of the stones was VERY limited. In fact, the map of the finds shows a distribution that was limited closely to disturbed surfaces, such as areas close to roads, cleared fields, and other developed areas. As is the case with strewn-fields, there are always the same questions: How were the limits of distribution determined, and how many man-hours of searching were spent in this determination? And finally,
4) Yes, the stones are of irregular form. Most have smooth, rounded corners. But, are there any other possible mechanisms which will "round the corners" of clasts, however rare, other than falling from space?
How about the possibility of the rocks falling out of a hot cloud of ash that had erupted from a nearby volcanic (andesitic) vent? Extremely hot, pyroclastic flows known as, "nuées ardentes", have been known to travel 7 km and to melt the exteriors of solid rock. Could these rocks have been picked-up by the gravity-flow and then deposited (dropped) onto glaciers, where they were preserved in ice for millennia, devitrifying their glass-coating, and eventually, gently melting out onto the top of the glacial deposits? Movement while the glacial ice melted could be an explanation for the dense accumulation of the stones.
Couldn't there be other possibilities? Or, is the "meteoritic origin" the best explanation?
The point is that for the next ten years nothing was published to resolve these questions. That is, until in 1977, Gary Huss made the last published reference (in passing) to the Takysie Lake stones in his paper titled, "Significance of the Yamato meteorites".
Here are his exact words:
[Reproduced from: Meteoritics, Vol 12, pg141, June 30, 1977]
" When one first begins to work with meteorites he learns that they have black
fusion crusts when they fall. He learns that the stones contain nickel-iron
metal which rusts after an indeterminate number of years and helps to turn
the crust from black to brown. He learns that after X number of years the
stony meteorite cracks, is invaded by water, and falls into crumbs, which
become part of the soil.
One learns these truths and feels competent to deal with most field
problems. But what one has learned to this point is not the whole story.
Many meteorites lose their crust long before they crack and fall apart.
Some meteorites, such as the larger pieces of Paragould, have little or no
crust when they land on the earth. Some have very little nickel- iron metal.
Several are known that had NO nickel-iron metal when they fell. Their crusts
were not black but were either grey or straw-colored. That these meteorites
were seen to fall is fortunate. What they would have looked like after fifty
years in the soil, no one knows.
In the course of field work, some brown-stained stones are found that
contain grains of iron without nickel . Some stones are found which are
apparently granite, or some other identifiable rock form, that are enclosed
in an apparently melted crust. The prime example of this is the Takysie Lake,
British Columbia, Canada, stones which have a glassy crust, are scattered
over a glacial moraine in the manner of meteoritic distribution, and which
show evidence of rather rapid decay wherever the crust has been detached.
They contain no nickel-iron, are made of an agglomeration of glassy material
containing small crystallites mixed with fragments of crystals, reminiscent of
the appearance of a basaltic tuff. Most of the glass does not seem devitrified,
which indicates that the formation took place in air rather than in water and
that the material is of fairly recent age. The glassy crust is composed of an
inhomogeneous mixture of two silicates common to the stones. There is an
almost complete lack of radiogenic nuclides, which indicates that the stones
had a short space history, if any, and that they may in fact have been buried
until recently (Nininger and Huss 1967). "
The point that Huss was making, was that we should be prepared to expect the unexpected. And that the recovery data from the Yamato (Antarctic) meteorites, having had a long terrestrial residence in the ice, might tell us something about meteorites that we were otherwise missing.
Well, two Antarctic meteorites found in 2006 certainly could qualify: GRA 06128 and GRA 06129 (Achondrite-ung) -- are uniquely different from "any known achondrite, including those of planetary origin". The composition of these two meteorites shows that an andesite-like melt can form from an undifferentiated parent body. And although these stones were protected from weathering while residing in Antarctic ice, their interior were "very weathered, to a rusty or yellow-ocher color", similar to the Takysie Lake stones. But the bad news is that, even though their interiors were badly weathered, the fusion-crust was still black and glassy, unlike the devitrified exteriors of the Takysie Lake stones.
Takysie Lake stone #TL29 found in 1991. There is a subtle hint of flow-lipping along the upper edge.
Close-up of a portion of a weathered surface on the #TL29-stone depicted above. Can't tell whether there is soil-clay encrusted on this surface, or if this is palagonite-clay from a devitrified fusion-crust.
Now getting back to that specimen of Takysie Lake that I purchased, as fate would have it, I soon discovered that there were other collectors of Takysie Lake specimens with the same curiosity and questions about these stones.
