New "Atacamaite" Impact Glass!
©N. J. Lehrman 12/08/2014, updated 2/19/15

A couple of years ago word started to leak out of Chile regarding a new "tektite strewn field" in the central Atacama Desert. I have finally acquired a fine lot of superb cherry-picked specimens, and they are exciting!

Firstly though, I do not think these are tektites, but rather, a fine impact glass that sits nicely on the shelf next to Irghizites and Wabar glass. Further, in our collection, this new material takes its rightful place as representatives of the tiniest little jets of glass ever squirted from the white-hot furnace of an earth/asteroid collision. There were surely numerous smaller events, but these produced a hail of mechanical pebbles and a cloud of dust. No ejected glass. Atacamaites may define the (current) lower threshold limit for squirting glass!

 (original artwork inspired by visions of squirting glass. © N.J.Lehrman 2014, all rights reserved). At the right is as fine a selection of Atacamaites as you can ever hope to see in one place. We have acquired specimens from three different sources, and estimate that we sorted through some 3000 to 4000 pieces to select these top-shelf prizes. Most of these are for sale below. A few are our keepers (and I will tell you that I paid $350 for one of those shown above! You'll have to guess which one---).



Of the sample reported in a recent abstract, specimens ranged up to 35 mm in maximum dimension and had a mean weight of about 500 milligrams (Devouard, et al, 2014). The first lot we acquired is probably not random or truly representative, but the mean of the pieces was 0.58 gms with a range of 1.2 (fragment) to 0.3 gms. In a world where the bragging rights usually go to the biggest known, these are noteworthy for their small size.

Fully two-thirds of these little bits show either mostly complete morphology or enough skin to infer that they are nearly full diameter bits. Atacamaites began life as little squirting fingers of incandescent (but soon to be black) glass. These jetting rivulets of fire were seldom larger than half the diameter of a pencil. Reportedly, they are found over an area of some 20 square kilometers, so these must've been truly high-pressure squirts. Can you picture this viscous spray of orange-yellow-white molten glass streaking from the unthinkable place where the kinetic energy of a massive body moving at tens of kilometers per second met an immovable object (earth) and flashed at an instant into shock waves and heat radiating outward at velocities that left all sound far behind? Consider the instantaneous release of "more energy …than the whole Earth releases (through volcanism, earthquakes, tectonic processes, and heat flow) in hundreds or thousands of years." (French, 1998, p. 7). That's a description of a moderate-sized impact!

The closest analogs of the Atacamaites are Irghizites, Wabar glass, Darwin glass, and Aouelloul glass. While each is unique in some ways, there is considerable overlap in the character and morphologies of these five impactites. Oddly, no source crater has yet been recognized for the Atacamaites. The other four are found in and immediately around obvious craters (Darwin is scattered over a somewhat larger area than the others). There is no reason to think that the Atacamaites were ejected long distances from their source impact, and the area is one of the dryest places on earth---hardly a locality where you would postulate erosion sufficient to destroy the crater.

These are magical transport devices that can take us to a very special place, the interface of the passionate kiss between earth and space. These bits of glass are the tangible record of the galactic weather along earth's recent orbital path corkscrewing through space! Rocks rain from this sky, and some are planet-killers. Some spray glass. Some a few thousand meters, some a few thousand kilometers! Some have pieces they can reach in the cabinet and hold, imagining.

The detailed location of the strewn field has not yet been reported, but is expected to be detailed in a forthcoming technical publication currently in preparation. Dating of the impact age is currently underway, but no results have been released. The glass is relatively dry at about 130 ppm water. There is significant comingling of impactor material, with iron contents varying from about 5 to about 15 weight-%. In a nice piece of detective work, Devouard et al (2014) report that there is a positive correlation between Ni, Fe, and Co, with correlation coefficients that remain similar at all levels of Fe concentration. This strongly supports contamination of the glass by varying proportions of an impactor containing fixed proportions of Fe, Ni, and Co.

This multi-kilometer spray of tiny glass streamers begs a mental journey to the Australasian event, where billions of tonnes of glass objects weighing up to a kilogram or so flew a third of the way around the earth, some in near-orbit. Atacamaites and Australasians are partners at either end of the known spectrum of preserved vitrifying impact events.


If you have an array of impact glasses from those magical moments, make room at the "tiny" end of the shelf!

References

Devouard, B., P. and 16 others---(sorry, I got bored), 2014, A new Tektite Strewnfield in Atacama, Chile, 77th Annual Meteoritical Society Meeting (2014), Casa Blanca, abst. 5394.pdf (http://www.hou.usra.edu/meetings/metsoc2014/pdf/5394.pdf)

French,B.M., 1998, Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures, LPI Contribution No. 954, Lunar and Planetary Institute, Houston, 120 pp.

Also see "Meteorite Picture of the Day" November 7, 2014 (http://www.tucsonmeteorites.com/mpodmain.asp?DD=11/7/2014&WYD= )

An interesting small-scale feature of the Atacamaites is the quite widespread presence of little beads and pellets of glass that look to be welded to the surface of many of the larger pieces. These adhering bodies are tiny---the maximum dimension of the three examples shown are (top to bottom): 4.3mm, 2.6mm, and 1.8mm.


Here is our original listing. Several Specimens remain available. Our new acquisitions are shown in the second table.

sold items updated evening12/16/14 ; I wil try to keep this listing as current as I can. As soon as I get an order, I will update (provided I am at home----)

1 0.6 gms fragment. $25 sold
2 0.4 gms fragment. $25sold
3 0.7 gms fragment. $25sold
4 0.6 gms fragment. $25sold
5 0.4 gms fragment. $25sold
6 0.9 gms fragment. $25sold
7 0.5 gms fragment. $25sold
8 0.7 gms fragment. $25sold
9 1.2 gms partial ear-shape. Large (as they go---) $65sold
10 0.5 gms full diameter fragment $40sold
11 0.4 gms interesting tiny adhering spherical beads $50sold
T1,12 0.7 gms complex shape $45 available
13 0.9 gms large, weakly twisted. $45sale pending
T1,14 0.3 gms weakly bulbed droplet $55SOLD
15 0.5 gms Very much like Irghizites. $60sold
16 0.9 gms Large. Beaded skin $70sold
17 0.6 gms Nearly complete droplet $40sale pending
T1,18 0.3 gms cylindrical pellet $45available
19 0.5 gms Complete irregular droplet $45sold
T1,20 0.3 gms Slightly vesicular twisted flattened droplet $65available
T1,21 0.5 gms Cylindrical fragment $55available
22 0.3 gms Our best little teardrop $125sold
The following are listed in random order. I have generally ommitted any verbal description except in cases where the picture needs some help---
  T2, #1, $85  
  T2, #2, $50  
  T2, #3, $40  
  T2, #4, $105  golf-club teardrop
  T2, #5, $75  
  T2, #6, $65  
  T2, #7, $115  
  T2, #8, $ 65  
  T2, #9, $125  
  T2, #10, $55  
  T2, #11, $95  
  T2, #12, $135  Bent dumbell
  T2, #13, $55  
  T2, #14, $10SOLD  
  T2, #15, $75  
  T2, #16, $70  
  T2, #17, $40  about BB size pearl
  T2, #18, $130Sold  Best example of welded adhesion
  T2, #19, $100  Nose section of large drop. A large Atacamaite at 1.6 gms..
  T2, #20, $35sold  
  T2, #21, $35  
  T2, #22, $80  Tiny gem drop, approaching dumbell form
  T2, #23, $65  
  T2, #24, $30  
  T2, #25, $13  
  T2, #26, $25Sold  
  T2, #27, $145  Very symmetrical pill-shape
  T2, #28, $15  
  T2, #29, $40  
  T2, #30, $60  
  T2, #31, $55  
  T2, #32, $ 185  
  T2, #33, $150  At 2.3 gms, our biggest offering---
  T2, #34, $35  
  T2, #35, $12sold  
  T2, #36, $75SOLD  That' a hole in the middle!
  T2, #37, $65  That's another hole, just by a thread!
  T2, #38, $40  
  T2, #39, $14  
  T2, #40, $65  
  T2, #41, $18 sold  
  T2, #42, $60sold  Nice BB
  T2, #43, $35  
  T2, #44, $75  Quite a perfect little drop.
  T2, #45, $165  A big, slightly dished dumbell.
  T2, #46, $ 50  Fairly large vesicles exposed on both sides.
  T2, #47, $75  Very sweet and highly symmetrical teardrop
  T2, #48, $125  Big elongate drop
  T2, #49, $20  
  T2, #50, $55  Very cute bulbous teardrop.
  T2, #51, $100  Big 1.9 gm drop nose with welded beads
  T2, #52, $ 125  Great teardrop
  T2, #53, $45sold  Tiny, but great morphology.
  T2, #54, $65sold  
  T2, #55, $80  
  T2, #56, $12  
  T2, #57, $ 85  nice teardrop
  T2, #58, $50  miniature M&M shape
  T2, #59, $70  teardrop with flattened nose
  T2, #60, $20  a half-sphere
  T2, #61, $100 Perfect teardrop 
  T2, #62, $25  cylinder segment
  T2, #63, $8  
  T2, #64, $15  
  T2, #65, $175  nice dumbell.
  T2, #66, $85Sold  Nice pearl, a little bigger than a BB
  T2, #67, $30  
  T2, #68, $80  Quit a perfect teardrop
  T2, #69, $125 Beautiful big teardrop
  T2, #70, $85  great oval pearl
  T2, #71, $12  
  T2, #72, $12Sold  
  T2, #73, $8Sold  
  T2, #74, $65  
  T2, #75, $200  Great dumbell
  T2, #76, $75  Was this a tiny hershey's kiss morphology?
  T2, #77, $125  Great teardrop
  T2, #78, $35  
  T2, #79, $35  
  T2, #80, $ 35Sold  
  T2, #81, $40  half teardrop, flat base
  T2, #82, $65  bulbous teardrop
  T2, #83, $85  nice tear, somewhat bladed tail
  T2, #84, $45  interesting splatted form
  T2, #85, $150  nice dumbell.
  T2, #86, $85  
  T2, #87, $18  
  T2, #88, $65  
  T2, #89, $90  
  T2, #90, $100  Unique, like a tiny drip of candle wax.
  T2, #91, $70  nice pearl
  T2, #92, $95  perfect tear
  T2, #93, $90Sold  tear with lots of welded beads
  T2, #94, $85  nice tear
  T2, #95, $12SOLD  
  T2, #96, $75  perfect tiny tear
  T2, #97, $60  irregular tear