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NWA 2999 Ultra-Rare/Unique Angrite Meteorite 1.126g!

The Real Deal, Do Not Settle for Self-Proclaimed Pairings!


1.126 gram part slice of NWA 2999, the most interesting Angrite ever found. NWA 2999 was brought back from a Moroccan expedition in August of 2004. This meteorite was not recognized as being anything exceptional until April of 2005, when Greg Hupé found time to investigate the entire haul from this trip. After examining hundreds of suspected meteorites he found 12 complete stones totaling 392 grams that looked somewhat different from the rest. Nobody would have guessed these stones would turn out to be ultra-rare Angrites, because texturally they look completely different from what most would expect. A sample was liberated from one of the stones and sent to Northern Arizona Universityand a second sample from a different stone was sent to the University of Washington. Both laboratories found that the mineral compositions matched those of Angrites. A decision was made to sample and test each of the 12 stones because the potential for additional important findings is great.


NWA 2999 is unique in having unusual mineral compositions that mimic terrestrial processes leaving some scientists to believe these types of stones could have only formed on a planet-sized body. Unlike most of the other known Angrites, NWA 2999 was found to be a plutonic rock, meaning that it formed underground and was not extruded in a lava flow. Interestingly enough, this sample lacks vesicles. The magnitude of these findings prompted scientists to send off a specimen to the Carnegie Institution in WashingtonD.C. for oxygen isotope testing. The results confirmed that NWA 2999 is the 10th member of the unusual and scarce Angrite group. One look at the image below will demonstrate how important this kind of testing is, because these individuals look nothing like the other Angrites.

A few comments made by scientists:

"NWA 2999 is unique in many ways from other Angrites including LEW86010. I think we can make a valuable contribution to the understanding of Angrite origin/parent body characteristics!"

"This meteorite is unique among known Angrites. It is texturally very different from most Angrites in having a plutonic rather than volcanic or quench texture, and it lacks vesicles!"

Here is a copy of the now famous Mercury abstract:

Unique Angrite NWA 2999: The Case For Samples From Mercury
AU: * Irving, A J
Dept. of Earth and Space Sciences, University of Washington, Seattle, WA 98195 United States
Kuehner, S M
Dept. of Earth and Space Sciences, University of Washington, Seattle, WA 98195 United States
Rumble, D
Geophysical Laboratory, Carnegie Institution, Washington, DC 20015 United States
Bunch, T E
Dept. of Geology, Northern Arizona University, Flagstaff, AZ 86011 United States
Wittke, J H
Dept. of Geology, Northern Arizona University, Flagstaff, AZ 86011 United States
Hupe, G M
Hupe, A C
Angrite NWA 2999: A group of stones (totaling at least 2.4 kg) found in Northwest Africa in 2004 represent the tenth known example of the enigmatic angrite meteorites. Although most angrites have textures indicative of rapid cooling from melts, NWA 2999 has an overall plutonic, polygonal-granular texture (similar to Angra dos Reis and LEW 86010), but with distinctive large anorthite, spinel and recrystallized olivine porphyroclasts (up to 6 mm across) and 10-20 μm wide, discontinuous anorthite coronas around spinel grains (to our knowledge a feature unique among meteorites). The major minerals are calcic olivine (Fa39.8-41, CaO = 0.6-1.3 wt.%, FeO/MnO = 77-97) and Al-Ti-bearing diopside (Fs9.6-11.3Wo53-54, Al2O3 = 5 to 9 wt.%, TiO2 = 0.5 to 2.4 wt.%, FeO/MnO = 55-130), with subordinate Cr-pleonaste spinel (Cr2O3 = 4.7 to 8.7 wt.%, Al2O3 = 55 to 60 wt.%, Mg/(Mg+Fe) = 0.44-0.47) and pure anorthite (<0.02 wt.% Na2O), and accessory kamacite, troilite and S-bearing calcium silico-phosphate. Orthopyroxene, kirschsteinite and vesicles are absent. The anorthite coronas (and systematic compositional zoning in adjacent diopside and spinel) imply that this rock experienced solid state decompression from the spinel wehrlite to plagioclase wehrlite stability field, and last equilibrated at ~870°C and 6.7 kbar. Oxygen isotopic compositions of acid-washed samples by laser fluorination (mean of 3 analyses δ18O = 4.03, δ17O = 2.04, Δ17O = -0.086 +/- 0.01 per mil) are typical for angrites.
Are Angrites From Mercury?: Angrites are mafic to ultramafic "igneous" or metamorphic rocks that probably derive from a large, differentiated planetary body; yet, in the absence of any "ground truth" the possibility that they are samples from Mercury rests only on circumstantial arguments: (1) the virtual lack of Na implies a highly refractory planet (near the Sun?) (2) oxygen isotopic compositions are close to and parallel to the TFL (like planetary rocks from Earth, Moon, Mars and Vesta) (3) preserved corona textures in NWA 2999 require a parent body capable of km-scale tectonic uplift of lithospheric material (by thrust faulting?) (4) each angrite specimen is texturally different with a unique CRE age (5) the wide range in CRE ages (55 to <6.1 Ma) suggests that the parent body (APB) is large enough to be struck repeatedly and may still be extant (6) very ancient formation ages (>4.555 Ga) imply very rapid core segregation and cooling following APB accretion (consistent with contraction?) (7) dynamical calculations predict that ~1% of material ejected from Mercury could reach Earth (8) the limited shock effects may mean that some angrites, including NWA 2999, were ejected by spallation; others may be impact melts (could vesicles in some quenched specimens be trapped impact rock vapor?).
1028 Composition of meteorites (3662, 6240)
2041 Stable isotope geochemistry (0454, 4870)
3662 Meteorite mineralogy and petrology (1028, 6240)
6235 Mercury
6240 Meteorites and tektites (1028, 3662)
Planetary Sciences [P]
Fall Meeting 2005

We cannot guarantee this very low introductory level price will be around very long. You will not find a more reasonably priced Angrite anywhere. If you consider the potential for new findings these stones represent, an acquisition now might prove to be the bargain of the decade later. As studies continue to develop and more findings are confirmed or are made, we will provide updates. Expect to read or hear a lot more about these fantastic stones in the near future. This specimen comes with an identification card from The Hupé Collection guarantying its importance.

Click on the link below to see other great auctions:

http://search.ebay.com/_W0QQsassZraremeteorites

32400元台幣



 
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