Meteorite**NWA 13758; R3**42.031 gram gorgeous slice, rare type!!!

Description

Hello up for sale is NWA 13758 classified as a R3 chondrite. This gorgeous slice weighs 42.031 gram, with a fine polish to one side, Saw cut reveals a breccia with fragments up to ~2 cm set in a fine-grained matrix. Abundant distinct chondrules are visible throughout. Two main lithologic domains exist within this meteorite, one has a gray, unstained matrix, and the second has brownish-orange-stained matrix. Electron microprobe analyses were performed separately on the two main lithologic domains. Domain "A" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Very small grains of albitic plagioclase are present. Chromite, pentlandite, and troilite are ubiquitous. No metal or oxidized iron was detected. Domain "B" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Domain "B" appears to have slightly more chondrules than domain "A". Very small grains of albitic plagioclase were present. Ti-rich chromite, pentlandite, and Ni-bearing troilite are ubiquitous. No metal or oxidized iron was detected. This comes with 2 COA cards, Streaming meteorites and Mark Lyon and display case. Thanks for your interest and take care.
Name: Northwest Africa 13758
This is an OFFICIAL meteorite name.
Abbreviation: NWA 13758
Observed fall: No
Year found: 2017
Country: Algeria
Mass: 100 kg
Northwest Africa 13758 (NWA 13758)
Adrar, Algeria
Purchased: 2017
Classification: Rumuruti chondrite (R3)
History: A large group of identically appearing stones, found together, was purchased by a Saharan dealer from a nomad in Algeria and was subsequently acquired by Mark Lyon and Dustin Dickens. The original find was reportedly in the Tanezrouft Plateau, with the nearest town being Reggane, Algeria.
Physical characteristics: Approximately 500 pieces ranging in mass from <1 kg to >5 kg, with a total known weight of approximately 100 kg. Dark brown sandblasted exterior. Saw cut reveals a breccia with fragments up to ~2 cm set in a fine-grained matrix. Abundant distinct chondrules are visible throughout. Two main lithologic domains exist within this meteorite, one has a gray, unstained matrix, and the second has a brownish-orange-stained matrix.
Petrography: (C. Agee, UNM) Chondrite with mean apparent chondrule size 350±240 µm (n=21) set in abundant matrix (~35 vol%). Electron microprobe analyses were performed separately on the two main lithologic domains. Domain "A" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Very small grains of albitic plagioclase are present. Chromite, pentlandite, and troilite are ubiquitous. No metal or oxidized iron was detected. Domain "B" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Domain "B" appears to have slightly more chondrules than domain "A". Very small grains of albitic plagioclase were present. Ti-rich chromite, pentlandite, and Ni-bearing troilite are ubiquitous. No metal or oxidized iron was detected.
Classification: Rumuruti chondrite (R3). Domain "A" is approximately R3.7 and domain "B" is approximately R3.9, based on olivine coefficient of variation (CV) after Bischoff (2000).
Specimens: 1127.72 g complete stone, and a 57.69 g full slice from a different complete stone, are on deposit at UNM. Mark Lyon holds the main mass including a total of 14 pieces weighing 19.84 kg, Dustin Dickens holds ~60 kg of medium to small stones.
Writeup from MB 111:
Added notes for NWA 13758
(C. Agee, UNM) The total weight of the R chondrite described here, under the name NWA 13758, was originally stated to be 100 kg. It is possible that other R chondrites from northwest Africa with official names, listed as found or purchased since 2017, could be stones taken from this same 100 kg. According to Dustin Dickens (pers. comm. to Carl Agee, 2021), the total mass of paired stones is likely to be about 200 kg. Assuming accurate pairings of NWA R chondrites could be established, their published masses should not be added together to determine the total recovered mass from the NWA 13758 strewnfield, as the same stones would likely be counted more than once.
Bibliography:
Bischoff, A. (2000) Mineralogical characterization of primitive, type-3 lithologies in Rumuruti chondrites. Meteorit. Planet. Sci. 35 699-706 (link)
Data from:
MB110
Table 0
Line 0:
State/Prov/County:Adrar
Origin or pseudonym:Tanezrouft
Place of purchase:Algeria
Date:P 2017
Mass (g):100000
Pieces:500
Class:R3
Shock stage:S2
Weathering grade:W1
Fayalite (mol%):36.6±8.4, 38.7±5.8
Ferrosilite (mol%):21.4±6.8, 10.0±7.7
Wollastonite (mol%):0.9±0.5, 2.0±1.8
Classifier:C. Agee, UNM
Type spec mass (g):1185.41
Type spec location:UNM
Main mass:Mark Lyon
Comments:Submitted by C. Agee
Science direct says:
Abstract
R chondrites are among the most oxidized chondrite groups; they also have the highest Δ17O values known in whole-rock meteorites. We analyzed R chondrites (six Antarctic, four hot-desert) by instrumental neutron activation analysis. Data for one of the former and three of the latter show large weathering effects, but the remainder show only moderate scatter and permit us to determine trends and mean compositions for the group. Bulk R-chondrite compositions are similar to those in H and L chondrites, but the concentrations of several volatiles, especially Se and Zn, are higher; the more volatile the element, the higher the enrichment in R chondrites relative to H and L.
Petrologic types in R chondrites extend as low as 3.6. We determined olivine compositional distributions and studied opaque oxides in 15 R-chondrite thin sections, including a newly discovered R4 clast in Bencubbin (adding to the diversity of chondritic clasts in this polymict breccia) and an R clast in CM2 Murchison. Opaque oxides in R chondrites include nearly pure magnetite, Al-rich chromite, magnetite–chromite solid solution, nearly pure chromite, and ilmenite. This diverse set of opaque phases reflects differing aqueous-alteration conditions.
The least equilibrated R chondrites contain nearly pure magnetite but the spinels in metamorphosed R chondrites contain additional components (e.g., Cr2O3 and Al2O3 and some minor cations). The NiO content in olivine correlates with the magnetite component in magnetite–chromite solid solution in equilibrated R chondrites and is a function of the degree of oxidation. The absence of metallic Fe in A-881988 and LAP 031156 indicates a high degree of oxidation; the relatively low-FeO (Fa35) olivine in these rocks in part reflects the conversion of Fe2+ to Fe3+ and its partitioning into magnetite. Oxidation trends in R chondrites are affected by both aqueous alteration and thermal metamorphism. The differing degrees of oxidation in this group reflect differences in local environments on the parent asteroid.
Chondritic meteorites are undifferentiated fragments of asteroids that contain the oldest solids formed in our Solar System. Their primitive, solar-like chemical compositions indicate that they experienced very little processing following accretion to their parent bodies. As such, they retain the best records of chemical and physical processes active in the protoplanetary disk during planet formation. Chondritic meteorites are depleted relative to the sun in volatile elements such as S and O. In addition to being important components of organic material, these elements exert a strong influence on the behavior of other more refractory species and the composition of planets. Understanding their distribution is therefore of key interest to the scientific community. While the bulk abundance of volatile elements in solid phases present in meteorites is below solar values, some meteorites record volatile-rich gas phases. The Rumuruti (R) chondrites record environments rich in both S and O, making them ideal probes for volatile enhancement in the early Solar System. Disentangling the effects of parent-body processing on pre-accretionary signatures requires unequilibrated meteorite samples. These samples are rare in the R chondrites. Here, I report analyses of unequilibrated clasts in two thin sections from the same meteorite, PRE 95404 (R3.2 to R4). Data include high resolution element maps, EMP chemical analyses from silicate, sulfide, phosphate, and spinel phases, SIMS oxygen isotope ratios of chondrules, and electron diffraction patterns from Cu-bearing phases. Oxygen isotope ratios and chondrule fO2 levels are consistent with type II chondrules in LL chondrites. Chondrule-sized, rounded sulfide nodules are ubiquitous in both thin sections. There are multiple instances of sulfide-silicate relationships that are petrologically similar to compound chondrules, suggesting that sulfide nodules and silicate chondrules formed as coexisting melts. This hypothesis is supported by the presence of phosphate inclusions and Cu-rich lamellae in both sulfide nodules and sulfide assemblages within silicate chondrules. Thermodynamic analyses indicate that sulfide melts reached temperatures up to 1138 °C and fS2 of 2 x 10^(-3) atm. These conditions require total pressures on the order of 1 atm, and a dust- or ice-rich environment. Comparison with current models suggest that either the environmental parameters used to model chondrule formation prior to planetesimal formation should be adjusted to meet this pressure constraint, or R chondrite chondrules may have formed through planetesimal bow shocks or impacts. The pre-accretionary environment recorded by unequilibrated R chondrites was therefore highly sulfidizing, and had fO2 higher than solar composition, but lower than the equilibrated R chondrites.Chalcopyrite is rare in meteorites, but forms terrestrially in hydrothermal sulfide deposits. It was previously reported in the R chondrites. I studied thin sections from PRE 95411 (R3 or R4), PCA 91002 (R3.8 to R5), and NWA 7514 (R6) using Cu X-ray maps and EMP chemical analyses of sulfide phases. I found chalcopyrite in all three samples. TEM electron diffraction data from a representative assemblage in PRE 95411 are consistent with this mineral identification. TEM images and X-ray maps reveal the presence of an oxide vein. A cubanite-like phase was identified in PCA 91002. Electron diffraction patterns are consistent with isocubanite. Cu-rich lamellae in the unequilibrated clasts of PRE 95404 are the presumed precursor materials for chalcopyrite and isocubanite. Diffraction patterns from these precursor phases index to bornite. I hypothesize that bornite formed during melt crystallization prior to accretion. Hydrothermal alteration on the parent body by an Fe-rich aqueous phase between 200 and 300°C resulted in the formation of isocubanite and chalcopyrite. In most instances, isocubanite may have transformed to chalcopyrite and pyrrhotite at temperatures below 210°C. This environment was both oxidizing and sulfidizing, suggesting that the R chondrites record an extended history of volatile-rich interaction. These results indicate that hydrothermal alteration of sulfides on the R chondrite parent body was pervasive and occurred even in low petrologic types. This high temperature aqueous activity is distinct from both the low temperature aqueous alteration of the carbonaceous chondrites and the high temperature, anhydrous alteration of the ordinary chondrites.