Accretion Desk

Witnessed Fall: Pirgunje, Bangladesh

• August 15, 2010

An August 1882 Witnessed Fall: Pirgunje, Bangladesh

No Next of Kin

Pirgunje and its Anticedents

Pirgunje

Falling 128 years ago this month, the L6 chondrite Pirgunje reminds, us, well me anyway, why meteorites are coveted in collections. 

Even thought the crust and matrix of Pirgunje is similar to many other chondrites, facts including the age of this fall, its sub-kilo TKW, its low collection distribution, the large size of this slice, the abundance of crust, and that a vast majority of the single Pirgunje stone is still intact makes this particular collection specimen a real trophy meteorite.

The thin description surrounding the Pirgunje meteorite extracted from a 1889 letter barely tops 25 words:

“A stone labeled “Pirgunje, 29.8.82″, was sent from India to E.A. Pankhurst of Brightonby a man who had no knowledge whatever of it or its antecedents.”

Pirgunje is not the oldest witnessed fall in Bangladesh, but it does have the smallest total known weight–but not by much. Interestingly, of the eight meteorites claiming Bangladesh home, all are falls with two of the meteorites (coincidently both falling in 1935) making up 80% of the Country’s Total Meteorite Mass (CTMM).


Pirgunje

With 50% of this partial slice’s edge crusted it really doesn’t get much better than this without the upgrade to a complete slice. 

When a meteor goes through puberty, it grows fusion crust and leaves behind its vagabond lifestyle. Once on the far side of its atmospheric rite of passage, the meteorite breaths oxygen and absorbs water until old age catches up with it.

Some lucky meteorites live a luxurious life bathed in nitrogen and venerated by lab coat wearing humanoids, while others are hacked and beaten to pieces before being sold into thralldom becoming nothing more than personal property.

Falling in the year of Charles Darwin’s death, the evolution of my slice of Pirgunje stops here hopefully remaining forever as it looks today.

Bangladesh has a colorful history to say the least. When when one overlays the region’s history of recovered meteorite falls across the cultural events of the area, a curious picture develops. All known meteorites from Bangladesh fell in the span of years between the Indian Rebellion of 1857 and the end of British colonial rule in India. No meteorites before 1863 and thus far none after 1940.

In specific, of the eight witnessed falls in Bangladesh, seven are ordinary chondrites (four L6s, one H5, one H6 and one LL3-6), and the only non-chondritic outlier is a mesosiderite named Patwar.


Pirgunje

With L6 chondrites, you have to enjoy what’s available. In the case of Pirgunje there’s not much action. Pictured above is the intersection of a metal inclusion with a dark, likely shocked carbonaceous area. 

The 6 in L6 basically means good luck finding a chondrule, but the L, although meaning a lower concentration of iron, does not translate to a fruitless search for any element with 26 protons.

Bangladesh is a country where almost a third of it floods each year during the four month monsoon season beginning around June first. It would be easy to blame the weather for why there are few Bangladesh meteorites, however something seemingly contradictory appears when comparing the monsoon season to the calendar of Bangladesh meteorite falls. First, June, July, August, and September are active monsoon months so those months should be the least productive for witnessing and finding meteorites. However, the fall days for Bangladesh’s meteorites are March 27, May 14, May 23, July 29, August 7, August 11, August 29 and October 22.

That means that half of the witnessed falls fell during the monsoon season, and six non-monsoon months offered up no meteorites. So it seems there is something else at work here. Any ideas?


Pirgunje

Posing with a crooked smile, the partial slice of Pirgunje represents the second largest piece in any collection anywhere. 

Not surprisingly, the main mass of Pirgunje, as listed in the Catalogue of Meteorites, resides as a 732g specimen in the Natural History Museum in London.

Beyond that, 28g are listed in the Field Museum collection, 23.1g in Canada, 23g in at the American Museum of Natural History, 16.2g in Calcutta, 9g in Vienna, and 3.8g for the Vatican. What does all that mean? Not much except that the piece in my collection is second largest piece of Pirgunje in the world. Or, as I like to think of it, since the main mass is still 87% of the original mass, my piece is the largest slice* in the world.

*Subject to change without notice.


Pirgunje

Back in the early 1990s, Blaine Reed acquired meteorites from the estate of the late Terry Schmidt. From what I have been told, Mr. Schmidt was able to obtain some remarkable samples of very rare meteorites in a quest to study fusion crust, and it is my assumption based on the December 1992 acquisition date that this slice of Pirgunje was one such Schmidt specimen.

The country of Bangladesh is about the size of the US state of Iowa. Bangladesh is surrounded overwhelmingly by India with good dose of the Bay of Bengal and a smidgen of Burma. It’s meteorite fall history over the past one hundred and fifty years is full of fits and starts, but today it seems totally stalled out with the most recent meteorite fall 70 years ago. While for some meteorite collectors that makes specimens from Bangladesh all the more desirable, but to me it means those collectors need to take a closer look at the facts because Iowa hasn’t had a witnessed meteorite fall since 1890!

 

Until next time….


The Accretion Desk welcomes all comments and feedback. accretiondesk@gmail.com


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Column: Accretion Desk

Martin Horejsi

About the Author

Dr. Martin Horejsi is a Professor of Instructional Technology and Science Education at The University of Montana. A long-time meteorite collector and writer, before publishing his column The Accretion Desk in The Meteorite Times, he contributed often and wrote the column From The Strewnfields in Meteorite Magazine. Horejsi is currently a monthly columnist in The Science Teacher, a journal by the National Science Teachers Association. Horejsi specializes in the collection and study of historic witnessed fall meteorites with the older, smaller, and rarer the better. Although his meteorite collection once numbered over a thousand pieces with near that many different locations, several large trades and sales have streamlined the collection to about 250 locations with all but 10 being important witnessed falls. Many of the significant specimens in Horejsi's collection are historic witnessed falls that once occupied prominence in the meteorite collections of Robert A. Haag, James Schwade, and Michael Farmer. Other important specimens were acquired through institutional trades including those from The Smithsonian Institution, Arizona State University, and other universities.

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