Meteorite Times Magazine

Meteorite Times Magazine Contents Paul Harris

Featured Articles Accretion Desk by Martin Horejsi Jim’s Fragments by Jim Tobin Meteorite Market Trends by Michael Blood Bob’s Findings by Robert Verish Micro Visions by John Kashuba Norm’s Tektite Teasers by Norm Lehrman Mr. Monning’s Collection by Anne Black IMCA Insights by The IMCA Team Meteorite of the Month by Editor Tektite of the Month by Editor

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Meteorite Times Magazine The Chiang Khan Meteorite Fall: A Gift That Just Keeps Giving Martin Horejsi

At 5:30 in the morning on November 17, 1981, a f ireball exploded high above the citizens Ban Klang and Chiang-Khan in the province of Loei in Thailand. Loud thunderous reports rolled across the land right bef ore a shower of stones pelted the landscape.

My pleasantly oriented individual of Chiang-Kahn sits atop a one-cm cube facing away from the center of the earth.

Scientists arrived on scene several days af ter the locals had gathered up all the easy-to-f ind pieces that amounted to about a third of a kilo in the f orm of 31 separate pieces with the largest at 51 gram.

A couple weeks later another piece was f ound but that one weighed more than twice that of all the previous material amounted. So with the additional 800g individual, the total known weight of Chiang-Khan unof f icially broke the one kilogram mark. Oddly, the TKW of this H6 chondrite is usually reported as 367 grams, or as the initial amount f ound shortly af ter the f all.

But the TKW story continues. In 2000, a f ellow named Oliver Alge mounted a week-long expedition to the strewnf ield. That week turned into several months. Oliver recounts his story online and in a paper that accompanied many of the specimens that he sold as part of f und-raising ef f ort. More on that ef f ort is available on Oliver’s website.

Fund raising with meteorites is not a new thing but is relatively rare. I wrote about my experience with what I called “Bakesale Juanchings” or small individauls f rom that f amous f all that were collected by students and teachers, then brought to America to be sold at the Tucson show. I was lucky to play a small part in that event buy buying their stones, and then selling them to recover my cost since my money was already headed back to the schools in China. Here’s some inf o on that f rom a previous Meteorite Times article.

This is a excerpt of Oliver’s Chiang-Kahn story as described on his website.

“Due to the political circumstances prevailing in Laos at that time, there are hardly any testimonies about this meteorite fall from there. My Chiang-Khan expedition 2000 was initially intended to last one week only, but actually I spent the whole time from November till the end of February 2001 (and again 6

month) in the strewnfield and was able to shed some light into this darkness.

I met a Laotian army officer who, right after the fall, was entrusted by the government with the task of seizing all fallen stones from the locals (threatening people with punishment!), in order to hand these specimens over to the authorities in Vientiane. People were told that this was dangerous Thai material.

Subsequently, the specimens are said to have been sold to the Soviets.’

A oriented meteorite shows the earth only one side during it’s fall. The crust of this Chiang-Khan individual is mostly intact and contraction cracks are visible.

“About half of the persons I interrogated declared a fall direction opposed to the one officially published: according to them, the fireball traveled southwards, to Thailand, coming from the North (Laos). With Thai observers, this variant of the reports is easy to explain: The tense political situation of those days induced the population to conclude that Laos had fired missiles against Thai territory during the night.

Due to the time of the fall, hardly anybody will have witnessed the event visually; the enormous explosion jerked people from their sleep and then engendered this story as their first thought.

I personally convinced myself at 5.30 AM in Ban Klang that except for a few dozen dogs sleeping in the streets, no more than a handful of people could have experienced this natural spectacle. Such fall reports by Laotians, on the other hand, can only be explained by yet another meteorite fall. The aforesaid Laotian army officer saw the fireball coming from the North. He was on night watch in Bagmee when, at about 3 AM, he saw the fireball detonate at an angle of some 45 degrees to the observer.

Almost all reports from Laos contain a different fall time and a North-South motion.”

Even as an H6, there are still small chondrules that poked their little spherical head up during reentry. The tiny round bumps make viewing Chiang-Khan under magnification much more interesting.

“A Thai fisherman gave a further fascinating account: at said time, he was on the Mekhong river, where he had cast his net to gather some fish for breakfast. He beheld the “devil’s ball” coming from South, and soon it vanished with a mighty burst. He had to seek shelter against the falling stones under a wool blanket, and the pieces that, in quest of a new home, were laying siege to his boat filled both his hands.

Afterwards, he said, he had thrown “the ugly black stones”, which for sure meant no good, into the river.”

For the serious meteorite enthusiast, the trailing edge of an oriented meteorite can be as interesting as the leading edge, sometimes even more so. Still, the cone or bullet-shaped front end is what really makes a valuable orientated specimen. And Chiang-Kahn does not disappoint.

“Nobody was able anymore to give precise indications as to the exact date of the event. Some 20 years ago it was, so they say, in the month of November, without doubt – that’s what I was told in the villages of the strewnfield. Whatever it was that happened then – one is led to presume a second meteorite fall on the same day or on the day after. According to recent research (isotope analysis), the two large specimens, which are in private Collection and in Chulalongkorn University, Bangkok, do not originate from the Chiang-Khan fall. They are believed to have been transported into Thailand from Laos. Two small pieces from Thailand were analyzed, one is H4 tending to H5; one was determined to be H5 in Japan, whereas the large pieces are H6. Most of all, the noble gas contents of the large specimens differ extremely from those of the Chiang-Khan pieces!”

Thank you again Oliver f or working in the f ield of Chiang Kahn in order to share the story with us, f or this is how meteorite history is made.

Until next time….

Meteorite Times Magazine Summertime Funtime James Tobin

Well summer is nearly over as I write this. It has been a f un season this year. Got in a couple trip to the desert f or astrophotography. Got some ceramic pieces made and with both those interests tried new equipment and techniques. I try to never stop learning new things. This article has f rankly been a problem. I have been so busy building Canon camera coolers and electronic f ocuser attachments and other things f or my star imaging that I have only been doing routine work with meteorites. Normal cleaning and cutting and diamond lapping. I have not been cutting into anything knew to f ind exciting unseen treasures. But I am waiting to hear back any time about three very cool stones that are out f or classif ication. I admit to being like a little kid when it comes to waiting f or laboratory work. I treat it like Christmas Day. I know there is a big reveal in the f uture when the results come back and it will either validate the personal guesses I have made about the stones or surprise me in a wonderf ul way perhaps.

I f ound a f ew months ago a very f riable stone while cutting some mixed up boxes of NWA material. It had a thick layer on the outside that was very crumbly bu,t it was f ull of wonderf ul chondrules some of which were quite large. I had to cut several slices to get into the heart of the stone and away f rom the outside that was f alling apart. Here is one of the outer slices that was starting to get better. It is one of the stone I am waiting to hear the results on.

I usually take a thin slice f rom the stones as I am making the samples to send of f f or classif ication. The thin slice goes to my lab in the garage and becomes a thin section which I examine while waiting on the real results. I have never sent just anything of f f or classif ication. It has always been the more special stones.

But in the f uture I may begin sending of f some the more ordinary material if labs will accept it.

I have described the process of making the thin sections in the past. It is f or me a hand made deal. I use a powered diamond lap f or the f irst part but af ter the material is starting to get thin I go to all by hand grinding. It takes a while and there are a lot of stops to place the slide in my polarized light viewer. But eventually I get to somewhere very close to 30 microns. I made a f ew thin sections this summer. They will f ind their way to the camera in the f uture to get imaged.

I just love all kinds of meteorites but have to admit I have a real sof t spot f or chondrule rich type 3 and 4 ordinary chondrites. I am just f ascinated by the way they look as thin sections in polarized light under a microscope. When I was young I got involved in commercial macro photography. I did work f or a group of local commercial artists and advertising f irms shooting all their small products f or print ads. I was struggling as a young man on my own to make ends meet and the extra money was really welcome. It was great training and today I still love getting in super close on my meteorites and f inding out what is there to capture photographically.

Seems like all my hobbies and interests f ind their way back to meteorites sooner or later. My ceramic art is made with meteorite dust mixed into the clay. I am playing currently with some exciting new projects that I hope will actually resemble meteorite slices when the mosaic tiles are done. My gold and silver jewelry work has been including more pieces of meteorite as time goes on.

This is the third level of experimentation f or my artistic vision of meteorites in clay. I have made thousands of tiny artif icial chondrules with about ten dif f erent mixtures and colors. I am about ready to try a real mosaic.

So does all this mean that I am obsessed with meteorites and need to f ind a program. Well maybe. But as f ar as I no there is no program like MA (meteorites anonymous). Maybe there should be.

If things go as currently planned I will get some meteorite hunting in later in the year. Has been a f ew months since I did any of that. So f ar retirement has been anything but rest f or me. I have been doing stuf f everyday that I had no time f or while I was working and that f or me is the best. I can spend a f ew days on each thing I love, and mix meteorites into most of them and work on astro images at night.

There is a Gold Basin Anniversary celebration coming up and going is on my short list of things I want to do. I have been thinking it is pretty dark out there I could take along some stuf f and maybe catch some astrophotos at night out there. That is another mix I have not done f or a while. Star images f rom a strewnf ield is sounding cooler every time I think about it. If I don’t f ind any meteorites during the day there is always the chance I will get some good images at night.

I guess at some point I will have to reign in these hobbies and just pick a couple, but f or right now I am enjoying being all over the place with them. They all stay f resh since I don’t do any of them all the time.

I know there was not a lot of substance in this article. Summer just does not seem like the time to be really serious and scholarly. So I apologize f or the glimpse into my daily retirement lif e. Promise the next article will have depth and inf ormation.

But now it is time to go and empty the kiln. Bye

Meteorite Times Magazine Bob’s Bulletin – Vol. 1 No. 3 Robert Verish

A newsletter for “orphaned” meteorites from the USA.

In my f irst Bulletin, I introduced the phrase “orphaned-meteorites f rom the USA”. I def ined these “orphans” as being unwitnessed-f all Ordinary Chondrite (OC) meteorite “f inds” that are recovered in the U.S. Unf ortunately, the vast majority of U.S. f inds are of this type.

I went on to write that these U.S. f inds were being orphaned f rom the f amily of “approved” meteorites f or the f ollowing reasons: 1) The lack of f unding f or U.S. researchers to authenticate, classif y, and document/record these U.S. OC f inds has resulted in several new [negative]; trends.

2) The increasing trend of commercializing the classif ying of meteorites by U.S. researchers has priced U.S. OC f inds out of the market, and 3) The increasing trend of U.S. researchers to turn away OC f inds, even when f inders of U.S. OC meteorites are willing to pay f or their classif ication.

In my 2nd Bulletin, I went into more detail about why I use the phrase “orphaned-meteorites f rom the USA”. I f ocused on the lack of U.S.-tax-dollar-f unding and why no f unding was going towards the classif ication of these particular meteorites. In hindsight, I now realize that I should have pointed-out that there is also a lack of f unding f or just authenticating and recording that a U.S. meteorite has been f ound.

This f unction should never be conf used with “classif ying” a meteorite, which is obviously way more labor intensive and costly.

My point is this: if you already have dedicated U.S. researchers (who have been approved f or classif ying

meteorites) and they are already having U.S. meteorite f inds being brought to them, and they are already deciding (visually) whether the f ind is an OC (and consequently, whether they will agree to classif y the f ind), then why not take one more additional step and record this f ind and have that data entered into some sort of U.S. OC database? Is it because there are no f unds allocated to do this f unction? Or worse, it actually is f unded, but f or some bureaucratic reason this f unction has been deemed “not important”?

[Yes, I know about “provisional” meteorites, but those are a separate issue. For starters, they are: 1) ONLY numbers that 2) STILL have to be f ormally assigned to pre-classif ied (and of ten unauthenticated) rocks that are 3) ONLY f rom DCAs (Dense Collection Areas). But DCAs can 4) ONLY be assigned af ter two or more meteorites have already been f ormally approved by the MetSoc (meteoritical Society) NomCom (Nomenclature Committee).

But what I am suggesting is much less involved, and although it may have to be done outside of MetSoc, it still could be done by volunteers f or U.S. OC f inds.]

A simple question that is of ten asked is, “How many of these ‘orphaned’ meteorites are there?” But, now you see why this question is so dif f icult to answer. We simply don’t know.

So, in order f or me to do my part to bring attention to this ongoing and growing problem, I will continue to gather data, and along with others, make a list of what we know to be “orphaned meteorites”.

To that end, in this newsletter-f ormat, I’m introducing the next f ive “orphaned” U.S. meteorite f inds: Newsletter for Orphaned Meteorites from USA – Volume 1 No. 3 — September 2015 Meteorite-Recovery Inf ormation Petrographic Descriptions Meteorite Specimen Petrographic Descriptions: N140531A N140531B N140531C N150814D N150814E

Example Petrographic Description Field ID Number

N140531A

Newsletter 01-3 Location Nevada, USA Thin-section ID Number VTBD Dimensions 3.5cm x 2.5cm x 2cm Weight 30.05 grams Type Specimen 6.4gram endcut – plus thin-section Class Ordinary Chondrite (quite possibly an LL6) <ahref =”??”name=”Weathering Grade”>Weathering Grade mid-range (but very likely above “W3”) <ahref =”??”name=”Shock Stage”>Shock Stage low (most likely “S2” or lower) Macroscopic Description — R. Verish This meteorite is a well-rounded, whole individual stone. The dark, grayish-brown exterior of this chondrite is covered 90% with a thick, relict f usion crust. Very little in the way of rust-spots. The interior is a dark-brown, compact matrix with very low metal-grain content, and f ew troilite grains. The chondrules and inclusions are not distinct, but don’t appear to be variable in size.

Thin Section Description — R. Verish The section exhibits a variety of chondule sizes (some up to 3 mm), but most are ill-def ined in a darkbrown, iron oxide-rich matrix of f ine-grained silicates, troilite and rare metal. Although the exterior of this meteorite has experienced only minimal physical weathering, the interior has undergone chemical weathering and is highly weathered. Very weak mosaic shock ef f ects are present. Silicates are equilibrated. This meteorite is probably a low-shock, equilibrated LL-chondrite.

USA Orphaned Met eorit e Images f or Specimen ID# N140531A

The above example is one way in which I can bring attention to what I predict will be an increasing number of unclassif ied meteorites f ound here in the USA. Hopef ully, attention will be drawn to what I see as a growing problem, and maybe some institution will of f er to help get some of these orphans classif ied and cataloged.

A newsletter for “orphaned” meteorites from the USA.

References: Meteoritical Bulletin: the search results f or all provisional meteorites f ound in “USA” – Published by Meteoritical Society – Meteoritical Bulletin, Database.

Meteorites of Calif ornia the list of f ormally-recognized Calif ornia meteorite f alls and f inds.

My previous articles can be f ound *HERE* For f or more inf ormation, please contact me by email: Bolide*chaser

Meteorite Times Magazine Micro Visions 3.00 John Kashuba

3.00 is a rarely given petrologic grade assigned to meteorites which experienced the lowest levels of thermal alteration on the parent body. (Aqueous alteration is another matter.) NWA 8276 L3.00 was assigned this grade based on laboratory tests and a study by Grossman and Brearley published in 2005.

Among many f indings the studyâ&#x20AC;&#x2122;s authors showed that at the onset of thermal metamorphism the average chromium content of iron rich olivine grains in chondrules was relatively high. As metamorphism proceeded those levels receded. And, at the same time, the variance among the values making up those averages changed â&#x20AC;&#x201C; starting with a narrow variance, widening then narrowing again with advancing metamorphism.

Combining these two characteristics, Grossman and Brearley presented a scheme f or classif ication of very low petrologic grade chondrites. See this graphically on Grossman and Brearley (2005) page 113, Fig. 15.

These characteristics and hence the method has the advantage of being resistant to the ef f ects of parent body aqueous alteration and terrestrial weathering.

The paper presents numerous other thermal metamorphism correlated phenomena including changes in core to rim Cr zoning in f erroan olivine grains, the development of distinct chromite inclusions, the migration of troilite and the expulsion of sulf ur f rom f ine chondrite matrix.

Most of this is invisible to our optical microscope but we are still able to enjoy this near-pristine meteorite in thin section.

One centimeter square polished surf ace. Packed chondrules and dark matrix. Incident light. NWA 8276 L3.00

Metal in and around a chondrule. Field of view is 3 mm wide. Incident light. NWA 8276 L3.00

A small metal-layered chondrule. Field of view is 3 mm wide. Incident light. NWA 8276 L3.00

Radial pyroxene chondrule with bleached rim indicative of parent body aqueous alteration. FOV = 3 mm wide. Incident light. NWA 8276 L3.00

Same RP chondrule in partially crossed-polarized light. FOV = 3 mm wide. NWA 8276 L3.00

Edge of the same altered RP chondrule in XPL. FOV = 0.3 mm wide. NWA 8276 L3.00

Overview in XPL showing that many chondrules are porphyritic olivine pyroxene chondrules. FOV = 8.6 mm wide. NWA 8276 L3.00

POP chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

POP chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

Polysomatic barred olivine chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

Barred olivine chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

Same barred olivine chondrule in plane-polarized light. No devitrif ication of the glass between bars is apparent. If the glass had started to crystallize we might have seen f ine needles extending f rom bars into the glass between them. FOV = 0.3 mm wide. NWA 8276 L3.00

Same barred olivine chondrule in XPL. The space between the bars is dark attesting to its glassy state. The sof tly def ined violet zones are places where the bars do not occupy the entire thickness of the thin section sample. The FOV = 0.3 mm wide. NWA 8276 L3.00

Meteorite Times Magazine Pseudotektites , a Tektite Teaser indeed!

Norm Lehrman

There is a f amily of remarkably similar (and usually controversial) natural glasses, including, Saf f ordites (aka” Arizonaites”)Colombianites, Healdsburgites, and Philippine Amerikanites, which I term “pseudotektites”. Placed side by side with the real thing, these look very much like tektites, but they almost certainly are not. We are of ten approached by individuals that are convinced that they have discovered new tektites or strewnf ields. Mostly, the claims can be readily dismissed, but the best-looking ones (pictured below), f orce us to critically review our tektite recognition criteria.

If those of us who know what tektites are should be asked to describe them to someone unf amiliar with them, I suspect all would include things like dimpled skin, aerodynamic shapes, composed of glass, black or green, not gray. There’s more, but these are prominent descriptors. However, the pseudotektites discussed in this article pose some challenges: • Their skin ornamentation—dimpling, pitting, grooving is ef f ectively indiscernible f rom that of true tektites.

• Their transmitted light color is of ten a smoky- lavender, not a color used in our def inition.

• Tektite-like morphologies are f airly common in the pseudotektites, particularly patties, biscuits, spheroids, and occasionally, teardrops (pictured below).

Assuming that we are correct that these stones under discussion are truly not tektites (and I am quite sure of that f act), then we must devaluate the diagnostic usef ulness of the most visually obvious f eatures of a tektite: skin-ornamentation, aerodynamic morphology, and basic dark glass composition. These are not peculiar to tektites.

In searching f or characteristics not requiring a laboratory that truly are (or are not) f undamental to the nature of a tektite, I have narrowed my observations to two key negative discriminants.

1) Gray transmitted light color and/or def lection of a delicately suspended magnet indicates the presence of crystalline magnetite. Tektites are given birth in a monstrous plasma f ireball. It is true and is probably a direct consequence of f ormation, that tektite glass is of extremely high purity, devoid of volatiles, and all constituent elements are f ully dissolved in the glass. There are never any primary crystallites at all.

2) Internal f low-bands or schlieren, when present, are invariably cut by the morphological surf ace in pseudotektites. Tektites (when unbroken) are complete primary bodies. Any internal f abric will conf orm with its bounding morphological surf ace. The teardrop-morphology Saf f ordite pictured below is by this criterion recognized as not being a primary aerodynamic f orm, but is rather an accidental erosional/corrosional similitude of a teardrop that is not complete, but is a remnant of what was once a very much larger primary (volcanic) domain.

The “morphologically-truncated banding” is a valuable recognition tool. A splashf orm tektite is a complete three-dimensional body, a f lying blob of molten glass enclosed entirely within itself . Every viscous taf f ylike internal band will honor the ultimate external bounding surf ace of the shape.

Consider a volcanic f low-dome complex composed all or in part of obsidian. Flow-banded domains may extend f or meters or even tens of meters. Now, in your mind, let that body chaotically f racture in the accumulated trauma of deep time and let advancing f ronts of hydration, devitrif ication, and other f orms of erosion eat into these f racture f aces until only a f ew “buttons” remain in the most central hearts of the boulders. What would they look like? My answer? Saf f ordites, Healsdsburgites, Colombianites, and (I think) Amerikanites.

(There is something of a scientif ic mystery hidden in the “Amerikanite” heading:. In my introductory photo, you will take note of an “Amerikanite” f rom the Philippines. H. Otley Beyer, f ather of Philippinites, routinely included in his specimen collecting inventories a heading entitled “Amerikanites”, and it is clear f rom his usage that he was ref erring to pebbles of terrestrial obsidian that he recognized as masquerading as Philippine tektites. Beyer, to my knowledge, never explains or def ines an “Amerikanite” in print. But I am willing to bet that it is a sibling of Saf f orf dites, Healdsburgites, and Colombianites! The one example in our collection f its nicely on that shelf ). These weirdities have a story of their own!

So what are pseudotektites if they are not tektites?

I believe these to represent the f inal skeletal traces of either very old obsidian or glass that was chemically unstable in its weathering environment.

All glass is geologically metastable and does hydrate, devitrif y and recompose (a new word, I think, but they do not strictly decompose, but rather transf orm f rom an amorphous state into a crystalline substance, essentially the opposite of decompose, hence, “recompose”) into clays over a f ew tens of millions of years. Logically, the last bits of remnant glass, geological moments f rom obliteration and oblivion, must have a corroded and etched skeletal appearance. They truly are quite magical objects in their own right.

These are the most ancient grandf athers of their species and when they are gone their ancestral rock will be extinct. We humans have belatedly learned to care about the passing of biological species in our spaceship ecosystem, but we f orget that even the mountains and rocks pass through their natural lif e cycles and are banished into time past.

These pseudotektites are the f inal survivors of their ancestral volcanic parents in the geologic Garden of Eden. As the strongest bits in the hearts of boulders, they are something of a crowning gem (—and the gemmy transparent lilac ones do indeed f acet into spectacular jewels!). Hold one and marvel. It is not a tektite. It doesn’t need to be. It is a stone with its own amazing story. It is one of the f inal generation of its kind bef ore ultimate extinction. A grandf ather boulder-heart!

A gem Colombianite!

A gem Colombianite!

Meteorite Times Magazine Understanding the Early Solar System through the Analysis of Meteorites: The Process of Maximizing Data while Minimizing Sample Destruction Ellen J. Crapster-Pregont

Ellen J. Crapster-Pregont 1,2 1. Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, 10964, USA. 2. Dept. of Earth and Planetary Science, American Museum of Natural History, New York, NY, 10024,

USA. Every year approximately 40,000 meteorites make it to Earthâ&#x20AC;&#x2122;s surf ace. This value is based on camera network meteor data (Halliday et al., 1989; Bland, 2005) and weathering studies of hot desert meteorites (Bland et al., 1996a,b; Bland, 2005) f or stones ranging f rom 10 to 106 g in mass. Of these, less than 10% are greater than 1 kg and less than 1% are collected, classif ied, and named (Fig. 1; based on values in Bland (2005) and the Meteoritical Society Bulletin Database). This small percentage is af f ected by our inability to retrieve many samples, such as ocean f alls, and by surf ace survival rates. Figure 1 breaks down this small percentage a step f urther to highlight how valuable chondrites, or meteorites f rom undif f erentiated parent bodies, are considering the inf ormation they hold about the highest temperature chemistry and processes in the protoplanetary disk as it started cooling and condensing, transitioning f rom gas and dust to crystalline solids, particularly the ref ractory (i.e. f ormed at high temperature) components observed in chondrites such as calcium- and aluminum-rich inclusions. These components preserve the most primitive inf ormation about our early solar system, and, as Figure 1 implies, only a small percent of a small percent of collected and classif ied meteorites contain this valuable inf ormation.

One of the greatest goals of a planetary scientist is to piece together chemical environments and physical processes that operated in our early solar system producing the planets and bodies that exist today. This is a Herculean task as much of the evidence lacks context or ref lects a more recent, alteration or def ormation history. Chondrites have bulk chemistries similar to that of the sun and preserve the history of the protoplanetary disk (i.e. gas and dust distributed in a disk-like f ashion around a proto-sun prior to planet f ormation) and their parent body within their components. Similar to other valuable meteorite groups, the subsets of chondrites with highest scientif ic value are only available f or research in small quantities. It is, theref ore, important to maintain a delicate balance between sample preservation and contributing to the scientif ic knowledgebase f rom collection and curation through analysis. A combination of non-destructive techniques through the entire sequence f rom sample selection, preparation, and analysis maximizes scientif ic return while minimizing material loss.

So what exactly can chondrites tell us? To answer this, we f irst have to consider the variety of components that make up chondrites (Fig. 2). These components are categorized broadly as: calcium- and aluminum-rich inclusions (CAI), amoeboid olivine aggregates (AOA), chondrules, metal and sulf ide nodules, and matrix. CAIs are highly ref ractory containing the greatest abundance of elements (i.e. Ca, Al, Ti) that condense f rom a vapor at high temperature, and minerals (e.g. corundum, hibonite, spinel, melilite) f ormed at high temperatures in the protoplanetary disk. CAIs exhibit a range of textures f rom primitive aggregates of tiny mineral grains to completely melted and recrystallized. AOAs typically have a core of highly ref ractory, CAI-like material but are then surrounded by olivine, a Mg-Si mineral that condenses at lower temperatures than the minerals in CAIs. As their name indicates, their texture is f ragmented and clustered, with many of the olivine-rimmed ref ractory clumps arranged together at dif f ering scales. Chondrules are diverse in composition but contain mainly Mg-Si minerals with varying Fe included to a varying degree.

Many chondrules appear to have been completely melted prior to accretion while some may ref lect a less melted, more agglomerated f ormation. Metal, generally Fe-Ni alloy, and sulf ides can be common or rare depending on the conditions of chondrite f ormation. Matrix is the f ine-grained material that holds all the chondrite components together. The percentage varies between types of chondrites and it is the most susceptible component, af ter metal and sulf ides, to the ef f ects of terrestrial alteration.

Dif f erent components and aspects of each component yield diverse inf ormation pertaining to characteristics of the early solar system and processes on parent bodies. Primitive, unmelted, CAI material holds the highest temperature record within its chemistry taking us back to a high-temperature protoplanetary disk (e.g. Ebel and Grossman, 2000; Grossman, 2010). Isotopic compositions can reveal the ages of components and def ine chemical reservoirs (e.g. Krot et al., 2005; Connelly et al., 2012; Holst

et al., 2013). Composition, crystallization characteristics, and other f eatures def ine the melting histories of components’ precursors including the temperature, duration, and extent of heating and potential f ormation processes (e.g. Jones and Rubie, 1991; Ebel et al., 2008; Krot and Bizzarro, 2009; Desch et al., 2010; Asphaug et al., 2011; Hubbard et al., 2012; Sanders and Scott, 2012; Johnson et al., 2015). Metal and iron content of certain minerals ref lect how oxidizing or reducing conditions were and whether this condition varied in space or time (e.g. Connolly et al., 2001; Beck et al., 2012; Schrader et al., 2013). Size and abundance distributions of components among dif f erent chondrite types distinguish unique f rom shared histories among chondrite types (e.g. Cuzzi et al., 2001; Hezel and Palme, 2010; Friedrich et al., 2014). These are just a f ew examples of critical datasets and their potential implications. All in, chondritic components’, chemistry, proportions, textures, etc. provide constraints f or the protoplanetary disk that astrophysicists try to model and f or the pre-dif f erentiation parent body processes in the early solar system.

Chondrites clearly contain a wealth of inf ormation that provides insight into the conditions of the protoplanetary disk and parent bodies even if only small percentages are recovered. A majority of meteorites studied today are collected through organized ef f orts, such as the Antarctic Search f or Meteorites, which f ocus on sites in hot and cold deserts where meteorites are both preserved longer and can be concentrated. Terrestrial weathering essentially removes value f rom a sample as it alters much of the chemical and mineralogical inf ormation to ref lect recent Earth surf ace rather than early solar system or chondrite parent body conditions. Falls are the most pref erred specimens but are rare (Fig. 1), do not encompass all types of meteorites, and still suf f er f rom terrestrial weather ef f ects. To the planetary science research group at the American Museum of Natural History (AMNH) is guided by the thought that every meteorite sample should be handled and curated in a way that extracts as much inf ormation as possible about every aspect of the meteorite while preserving the sample f or f uture use (Fig. 3), especially those samples that contain rare, valuable data about the early solar system.

At the AMNH, the analysis protocol f or recent work begins with a trip to the in-house CT scanner (GE VtomeX-S x-ray computed tomography scanner) in the Microscopy and Imaging Facility. This instrument utilizes high-powered x-rays to produce data that is reconstructed into a 3-dimensional (3D) density map of the sample. Obtainable resolution, measured as the edge length of each cubic volume element, or ‘voxel’, depends on sample size, or distance f rom source, and size of f ocal spot; i.e. the best resolution f or a sample 5x5x20 mm is ~4 micron/voxel on the scanner at AMNH (Fig. 3A and B). Resolution limits the types of analyses that can be conducted. Lower resolution allows virtual isolation (segmentation) and quantif ication of materials with signif icantly dif f erent densities (i.e. metals vs. silicates or chondrules vs. matrix) while higher resolution studies can dif f erentiate dif f erent silicate and oxide minerals (e.g. Ebel et al., 2008; Friedrich and Rivers, 2013; Russell and Howard, 2013; Tsuchiyama et al., 2013). The 3D visualization permits analyses done in 2D to be placed into context (i.e. whether the mineral is in the core or rim of the chondrule) which could greatly af f ect interpretations. Component relationships and abundances can also be directly calculated f rom the CT data (e.g. Friedrich and Rivers, 2013; Russell and Howard, 2013; Goldman et al., 2014). While this technique can guide sample preparation, 2D analyses of surf aces are still required to address a majority of the component-based protoplanetary disk and parent body processes conundrums.

During sample preparation, cutting is the step that results in the most unrecoverable sample loss. Typical diamond embedded rock-cutting blades lose a >100 micron thick slice of material. Use of a 20, 30 or 50 micron tungsten (W) wire saw (Princeton Instruments) minimizes the thickness of material lost. This ef f ectively minimizes sample loss and maximizes the number of surf aces that can be analyzed within a given piece of meteorite, a method called ‘serial sectioning’ (Fig. 3C; ps1B and ps2A are cut surf aces).

This technique permits >100 micron diameter components to be exposed on two mirrored cut surf aces while larger components can be sectioned in more than two adjacent sets of surf aces (e.g. Ebel et al., 2008). The wire saw also produces a smooth surf ace requiring minimal grinding when the sample is polished f or analysis.

Polishing is necessary to reduce surf ace topography which negatively af f ects most analysis techniques.

Some techniques, such as electron microprobe (EMP) analysis, require a polish f inished with 1 or 0.25 micron diamond solutions, while others, such as electron backscatter dif f raction (EBSD), require extremely good polishes adding a chemical etching component with the use of colloidal silica. Diamond is a pref erred polishing compound because it does not contaminate the sample with aluminum (Al) or silicon (Si) both which are of interest f or components in chondrites. Alcohol or mineral spirits are pref erred over water f or polishing and rinsing because water may cause oxidation, reactions, or dissolution of some minerals.

Successf ully prepared samples can be coated with a thin layer of carbon to make them conductive, a

necessity f or use in most electron beam instruments.

The Cameca SX100 EMP at AMNH uses two types of spectrometers: wavelength dispersive and energy dispersive, to generate elemental concentration data f or individual points or regions. Pixel-by-pixel element intensity maps (Fig. 3D) can be combined into red-green-blue (RGB) composites allowing dif f erentiation between types of inclusions and minerals in meteorites over large, region maps (>1 micron/pixel) or individual inclusions (1 micron/pixel). Figure 2 illustrates zoom in of dif f erent components and f igure 3E shows a component of interest outlined in white. Element intensities measured by the EMP are converted to oxide weight percent (wt%) via calibration against standards analyzed with the same instrument settings as the samples. A variety of sof tware, either customized or packaged, can be used to evaluate each inclusion pixel-by-pixel using element intensity maps and combinations of ratios and cation f ormulas. A phase map is produced with each pixel assigned a f alse color indicating mineralogy as determined by element intensities (Fig. 3F). Bulk chemistry, mineralogy, modal abundance, texture, and area are quantif iable f rom either region or individual inclusion maps (Fig. 3G). The choice of analysis sof tware will af f ect the time required f or sample preparation, calibration, data acquisition, and image analysis and this choice is made based on the scale and f ocus of the study.

Up to this stage of analysis the techniques (CT, wire saw, polishing, EMP) are minimally destructive to the valuable samples. The data are used to evaluate and compare chondrite component characteristics including chemical composition, mineralogy, and textures. So, with minimal sample loss many scientif ic questions (major element chemical environments, abundances of components in chondrites, the mineralogy of chondrite components etc.) regarding the protoplanetary disk and parent body processes can begin to be addressed. Our group uses this protocol to build databases that provide contextual and quantif iable inf ormation about the early solar system that is accessible f or reevaluation in the f uture. This preserves maximum data f or the limited primitive, pristine chondritic samples that have been collected and catalogued.

This database serves as a resource f or directing f urther analyses which can be more destructive or cost prohibitive (Fig. 3H). Electron backscattered dif f raction (EBSD) provides crystal orientation inf ormation which is used to understand crystallization and def ormation of mineral grains. Figure 4 depicts preliminary EBSD data that highlights twinning in metal f ound in a chondrule which will provide f ormation constraints (e.g. Crapster-Pregont et al., 2015). Secondary ion mass spectrometry (SIMS) is minimally destructive but may require travel and analysis costs as not all institutions maintain these instruments. Inductively coupled mass spectrometry (ICP-MS) requires either dissolving the sample into solution or blasting the point of interest with a laser while both can be done with minimal sample loss, this method may also require extra cost. Both SIMS and ICP-MS yield inf ormation about trace element abundances and even isotopic inf ormation yielding constraints on reservoirs and ages (e.g. Stracke et al., 2012; McCubbin et al., 2014) f or SIMS and ICP-MS respectively). Focused ion beam lif tout f or transmission electron microscopy (FIBTEM) can be used f or extremely high-resolution chemical and orientation analysis of relationships within and among minerals within a chondrite component (e.g. Stroud et al., 2002; Stroud et al., 2003). EBSD, SIMS, ICP-MS, and FIB-TEM are just a f ew techniques implemented by planetary scientists to obtain detailed data f rom chondrites to continue addressing questions about the early solar system. However, unlike the protocol described above, each of these techniques requires sample consumption to produce data. While valuable sample is lost, the initial context and basic inf ormation f rom the chondrite is preserved in datasets f rom the minimally destructive analysis techniques.

Even though f ewer meteorite samples exist in a catalogued database than are predicted to f all in a year, it is possible to optimize the analysis process with respect to the value of the chondrite and the inf ormation it contains. When combined these techniques (Fig. 3) reduce the amount of material lost and maximize the inf ormation obtained f rom a single meteorite sample. The larger set of data preserves contextual and quantif iable data f or each CAI, AOA, chondrule, metal nodule, and matrix while guiding f uture, destructive analysis. By using a series of instruments, visualizations, and sof tware protocols it is possible to begin to better understand the complexity of the protoplanetary disk, and planet f ormation processes preserved in meteorites with maximum conservation of these precious samples.

Acknowledgments: The Brian Mason Travel Award is sponsored by the International Meteorite Collectors Association f or the 2015 78th Annual Meteoritical Society Meeting. Research is supported by the National Science Foundation Graduate Research Fellowship Program grant DGE-11-44155 and NASA Cosmochemistry grant NNX10AI42G.

Fig. 1: Percentage bar representations demonstrate the rarity of and necessity to f ully analyze chondrites and their components. Percentages f or predicted annual impacts of meteorites (Bland, 2005) are f ar greater than those collected, classif ied, and catalogued (top bar: 2014 data f rom the Meteoritical Society Bulletin Database). When all meteorites in the Database are considered the remaining percentage bar comparison show: iron, achondrite, or chondrite; whether a f ind or the much less common observed f all; exhibiting parent body alteration or pristine; and whether the component is composed of minerals predicted to condense at highest temperature (ref ractory) in the protoplanetary disk. All percentages are based on number not mass.

Fig. 2: Backscattered electron image (BSE) of Moss (CO3.6) AMNH #5185 with examples of dif f erent components boxed with corresponding outset f alse color, 3-element red-green-blue composite images.

The 3-element combination Mg-Ca-Al clearly distinguishes calcium- and aluminum-rich inclusions (CAI; primarily blue and green), chondrules (primarily red), and amoeboid olivine aggregates (AOA; blue and green core with red surrounding) f rom each other. While metal appears black in the Mg-Ca-Al images the combination of Fe-Ni-S permits chemical variation observation f or the metal nodules and metal in the AOA. Matrix is a darker red color highlighted in the white box within the corresponding image of a dif f erent component.

Fig. 3: Preparation and analysis protocol f or minimizing sample loss and maximizing data. (A) Photo of Moss (CO3.6) AMNH #5185; (B) single CT slice, high density is whitest; (C) post-wire saw sections; (D) EMP element intensity maps f or aluminum (Al), calcium (Ca) and magnesium (Mg) with inclusion outlined; (E) RGB composite, note ease of distinguishing inclusion; (F) f alse color mineral map output: purple-spinel, red-olivine (olv), green-clinopyroxene (cpx); (G) quantitative data produced; (H) f urther destructive techniques possible using a high level of prior contextual knowledge (A-G).

Fig. 4: Electron backscatter dif f raction (EBSD) generated f alse color, reverse pole f igures maps f or a whole metal nodule (a; 2 Îźm/pixel) and higher resolution portion of a dif f erent nodule (b; 0.5 Îźm/pixel) in the second metal layer in the Acf er 139 layered chondrule. Color represents the orientation of the metal at each pixel described by the mixing chart in the center of the f igure where each apex is a dif f erent crystal axis. Small wire-f rame cubes highlight the orientation of various regions. Lamellar-like f eatures are twinning not artif acts of the polishing process. Image unmodif ied f rom (Crapster-Pregont et al., 2015) with permission.

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