Ureilite, diamond rich - Ureilit, diamantreich

Ureilites #

Ureilites are a rare class achondrites mostly rich in carbon often in the form of diamond

Ureilites are in contrary to many achondrites not igneous differentiates, but ultramafic meteorites, which are almost always highly fractionated.

They are composed mainly of magnesian olivine, pyroxenes (often occuring as pigeonite crystals), free (Ni-)Iron, graphite and diamond inclusions.

Their mineral and oxygen isotopic compositions suggest that they formed as residues from partial melting.

Despite the fact that ureilites have undergone a planetary differntiation history process, to some degree of surprise

they also have primitive characteristics (like presence of free NiFe and oxygen isotopic signature of primitive/unequilibrated solar system materials).

There textures is often medium- to coarse-grained. The black fusion due to high carbon content black.

As many ureilites contain poly-cristalline nano-diamonds, they are pretty hard to cut.

The ureilites are subdivided into two main groups:

(for space science highly interesting is the rare) polymict group:

(more common) monomict main group

Members of this group are built up of a mixture of distinct lithologies often highly different of each other in mineralogy

This fact and the specific values for noble gases may point to a regolith origin for polymict ureilites.

Except clasts of the monomict ureilite lithology, they may contain magmatic inclusions, explicit chondrules or relics thereof and other - in the context - sometimes odd materials and surprising mineral compositions, e.g. the extremely rare and interesting Ferro-Silicide Suessite:

To the best of my knowledge suessite was found on earth or in space so far only in polymict ureilites (with the exception of the monomict ureilite NWA 1241).

According to Keil et al. (1982)
Suessite was formed during the fall as a result of silica reacting with carbonaceous matrix, (Personal Note: likely by reduction)

Yukio Ikeda suggests in his abstract Petrology of an unusual monomict ureilite, NWA1241 that the suessite was produced from FeO-bearing olivine and Ni-bearing kamacite at temperatures around 1500–1400K and oxygen fugacity of 10 −18 –10 −20 bars.
Most ureilites experienced two-stage reduction. Stage-I reduction was a smelting process in ureilite parent bodies (UPB's) to form the framework of monomict ureilites. Stage-II reduction took place after catastrophic destruction of the UPB's to eject many fragmental blocks into space, where suessite (NWA1241) or Si-bearing kamacite (common ureilites) were produced together with the formation of reversely zoned olivines. (Yukio Ikeda et al)

(Vertreter dieser Gruppe bestehen in erster Linie aus grobkörnigen Olivinen. Begleitmineralien sind kalzium-armer Pigeonite (ein Pyroxen). Die dunkle kohlehältige Matrix besteht fast stets aus einem Gemenge der reinen Kohlenstoffvertreter Graphite and Diamant. Auch freies FeNI und Troilit sind häufig)

Please click below on underlined meteorite title names to see more detailled descriptions

Monomict Ureilite (unclassified) from Northwestern Africa: nice material: $8/gr

available: 4g, 16gr, 63gr

Almahata Sitta,
heterogenous material reaching from anomalous coarse-grained and porous ureilite
to material with more fine-grained and well-consolidated ureilitic texture
0,65g sold!
0.83g 7x7mm sold;
1.2g slice AURE coarse grained with tiny Suessite trace 13x13x3mm $550, 1.1g slice AURE medium grained 11x13x3mm $490

polymict ureilite, Name : DAG 319

(FeO/MgO) Dar al Gani , highly beautiful, diamonds!

Primitive clasts in the Dar al Gani 319 polymict ureilite: Precursors of the ureilites (Ikeda et al)

Lithic and mineral clasts in the Dar Al Gani (DAG) 319 polymict ureilite (Ikeda et al)

0,40g 5x5mm slice $29, slice 0.51g 6x7mm $53 ; 0,65g sold!

0.63g 7x7mm sold; 1.15g slice 10x13mm;

Price

1 bug box (appr.0.15g appr.5x3mm) : $ 13

comes complete with certificate!

DaG 868 - Ureilite (unshocked diamondrich)

Ureilites containing diamonds were always thought to have been formed by impact shocks.

PTS of DaG 868

A new type of Ureilite ( DaG 868 ) has been discovered and was published now.

The features of DaG 868 seem to suggest that reconsiderations about the origin and building history of ureilites are necessary now:

The Ureilite is containing fine-grained diamonds but olivines appear to be unshocked (show no evidence of undulose extinction!) -

Graphite found in pigeonite crystals in DaG 868 however contain diamonds!

This suggests that the diamonds have not(!) been formed by shock impact or chemical vapor deposition

and such raises major questions about building history of ureilites.

Catalytic transformation of graphite to diamond will be a mechanism to be considered for this new ureilite type.

Such DaG 868 falls in an own group of " weakly shocked diamonds "with" the presence of diamonds" with ALH 78019 and 78262..

History: A 40.03 g ureilite meteorite was found on 13th of April of 2000 by anonymous

finder in DaG in the Central Saharan desert.

Classification and mineralogy (H.Takeda,Chiba and M. Ohtsuki UTok):

the ureilite meteorite has a typical texture for ureilites consisting of anhedral to subhedral olivine and pigeonite (0.9 – 3 mm across);

Carbonaceous material forms rims around some grains or, in some cases, veins; one plate of graphite occurs within a large pigeonite crystal;

The interesting fact on this material is that the olivines appear to be unshocked compared to most ureilites, and have homogeneous cores (Fa20.6)

and reduced rims (Fa8) with high CaO contents (0.25-0.38 wt.%); pigeonite,Fs16.8Wo7.5.

X-ray diffraction and reflected light microscopy (T. Nakamura and T. Nakamuta, KyuU) confirm the presence of fine-grained diamonds in a graphite lath.

Specimens: main mass with anonymous finder; type specimens, 6.33 g, NSMT; 1.8 g,KyuU.

Ultrathin slices BB $35; 0.1g sold ; 0,24g; 0,8g 16x15mm slice; 0.5g sold

1,57g 30x14mm almost complete slice sold

3,7g segment

$350/gr

Please kindly ask for availability of slices: eric@mars.li

DaG 976 - polymict Ureilite with (prov.) CI inclusions:

1 meteorite of 32.033g was found 1999 Aug.20th

available are thin slices of 0,4g sold/traded, 1.4 g, 1,5g sold/traded

0.9g 18x16mm @ $175/gram

Please ask for availibility and price (limited supply) : eric@mars.li

DaG 977 - polymict Ureilite:

PTS of DaG 977

A total mass of 17g crust was found 2000 in the desert region of DaG, Al Juffrah

Available are slices of 0,1g sold; 0.41 g sold, 0,55g sold; 0.89g 14x12mm,

endpiece 1,3g @ $88/gram;

representative large slice of 1.7g $130S

Thin sections (PTS): $99/pce.

polymict ureilite - DaG 999

Found 2000 April 14

Numerous fragments totaling 2,106 g were found on 2000 April 14 in the sand desert

of Dar al Gani. Classification and mineralogy: (A. Greshake and M. Kurz):

a fragmental breccia with mineral and lithic clasts set into a ureilitic matrix

dominated by large olivines;

olivine core, Fa14.3-23.5; reduced olivine rims, Fa2.9-13.5;

mineral clasts are pigeonite, Fs14.3Wo8.5 and orthopyroxene, Fs9.3;

lithic clasts consist of fine-grained olivine (Fa22) and pyroxene

(Fs19.3Wo4.5) rich material;

shock stage, S3; low degree of weathering.

type specimen 20.8 g plus one polished thin section MNB

3g; 3.7g; 4.5g @$65/g; 76.8g; 111g

Price

Available only through us!

Special: polymict Ureilite DaG999 - 39.8g
fresh complete individual
80% black - blueish fusion crust

Top side is loosely covered with some original Saharan sand!

DaG999-39.8gI.jpg

polymict Ureilite (with Enstatite - pyroxene), polymict - Dar al Gani 1023

DaG 1023 is one of the world's most heavily shocked ureilites.

It contains the extremely rare Ferro-Silicide Suessite. This surprising ureilite displays also a few explicit chondrules.

Found August 19th 1999 , Dar Al Gani plateau Al Juffra.

A ureilite meteorite of 149 g was found by an anonymous collector in the Dar al

Gani desert. Mineralogy and classification (H. Takeda, Chiba; T.

Ishii and M. Ohtsuki, UTok): fragmental breccia, with lithic and

mineral clasts embedded in a cataclastic matrix of predominantly

ureilitic material. Lithic clasts and fragments include mafic

ureilitic material (olivine 86 vol. % and pyroxene 12 vol. %),

Na- rich plagioclase fragments

and rare subrounded, dark brown Na-, K- rich glassy grain

(SiO2 68 wt. %, Al2O3 13.6 wt. %, MgO 5.6 wt. %,

CaO 5.3 wt. %, Na2O 6.3 wt. %, K2O 0.8 wt. %). The pyroxene

composition ranges from En79Wo6 to En62Wo4 and En59Wo31; olivine

composition ranges from Fo90 to Fo75. The plagioclase composition

ranges from An13Ab85 to An33Ab62.

A slice of a lithic clast of 3.7 2.7 cm in size

(subsample ,02; 6.89 g slice), is one of the most heavily shocked ureilites known.

All mafic silicates are converted into very fine grained materials

with a granoblastic texture;

carbonaceous vein materials are lost from many grain boundaries;

glassy shock-vein materials are observed at some parts of the thin

section. Olivine (80 vol. %) is more abundant than pyroxene (20 %).

Pyroxene composition ranges from En86Wo2 to En77Wo10 and En69Wo6;

olivine composition ranges from Fo96 to Fo66. The ureilite meteorite is weathered,

with a brownish colour in hand specimen, but in thin section the

weathering grade appears to be very low. Specimens: type specimen,

20.752 g (including sample ,02), NSMT, one thin section, Chiba; main

mass with anonymous finder.

0.49g, segment; 0.58g slice sold; 1.1g sold; 2.8g slice 28x24mm ; 3.1g slice

no pairing - Available only through us!

polymict Ureilite - DaG 1047

A ureilite meteorite of TkW: 49.8 g was found 16-May-1999 by an anonymous collector in the Dar al

Gani desert.

Classification: Meteoritical Bulletin:

Comments: Approved 24 Jul 2007 Data from: MB92 Table 1

Shock stage: Mod ; Weathering grade: Moderate

contains the extremely rare Ferro-Silicide Suessite and shows a few explicit chondrules

Fayalite (mol%): 3.6-22.4, Ferrosilite (mol%): 3.7-22.4, Type spec mass (g): 10.2

Info: Classified: A. Greshake, MNB. Type specimen: MNB. Main mass: Anonymous.

Comments: Polymict breccia with fine-grained chondritic lithologies

only few small segments of up to 6mm max diam are left of this rare Ureilite type

Please ask for availibility (limited supply) : eric@mars.li erich.haiderer@chello.at

Dho 132 - Ureilite

available: thin slice 0.33g 7x7mm $30 ; 1g 12x14mm $70; 2.9g slice $190

Dho 836

1 fresh looking, oriented ureilite meteorite (split up in 1 big and 1 small pieces) with large greenish olivine clasts of 995g was found on 15.8.2002 in the sand desert

0.34g - 7x10x6mm fragment $48
1.4g 13x15mm beautiful slice $98; 3.1g- 20x26mm slice $199

rare type 2 Ureilite (such as Hajmah (a), Donga, or Dyalpur): Dho 837

Click for availibility

JaH 054 polymict Ureilite

1,4g slice 15 x11mm, endpiece 2.5g, $110 BB $16

Please ask for availibility erich.haiderer@chello.at

New! Very Unusual, Surprising: type 2 - Ureilite

Ureilite - NWA 1241

contains the rare mineral Suessite which is a very rare metalic mineral with the composition: (Fe,Ni) 3 Si with very low Ni content (appr. 1-3) indicating that this material is rather not from an asteroidic parent body.

type 2 - Ureilite (such as Hajmah (a), Dingo Pup Donga, or Dyalpur)

Classification and mineralogy: (F.Wlotzka, MPI, and M. Kurz, Germany)

TkW: 282g covered with fresh fusion crust.
Olivine and pigeonite grains (up to 1mm) are set in a pavement texture of smaller olivines containing finely dispersed metal grains.

Intermediate (type 2 - medium reduced! ) FeO/MgO ratio in olivine cores: Olivine has Fo 80-83 in the cores (with 0.7 -1.7% Cr2O3, 0.2-0.6% CaO).
Pigeonite has Fs 4-22, Wo 4-15, En 74-87, and 0.6-1.2% Cr2O3.

Carbonaceous matrix is rare, graphite occurs in fine-grained patches. Coarser white reflecting grains are Suessite, (Fe,Ni)3Si, with 13% Si, 2.5% Ni (range 1-4%), 1.1% Cr. This rare mineral is
abundant in NWA 1241and occurs as blocky grains or interstial vein-like forms. No kamacite and no troilite were found.

The mineralogy of NWA 1241 suggests that it was formed at extreme pressures of appr. 100 bars and equilibration temperatures of more than 1200°C!

This NWA 1241 is a valuable sample for understanding the thermal history of ureilites parent body.

NWA1241 is an unusual monomict ureilite, consisting mainly of pigeonite, olivine, suessite, and carbonaceous materials.

The modal ratio of pyroxene/(olivine+pyroxene) is higher than those of common monomict ureilites.

Metallic phases in NWA1241 are mainly suessite, although metals in common ureilites are mainly kamacite.

The high ratio of pyroxene to olivine and the abundant occurrence of suessite make the meteorite unusual.

Minor weathering.

Type specimen: 20.5g MPI.

NWA 1241 9.005g.jpg NWA 1241-2 slices 1g.jpg

0.2g slice 4x5mm with crust sold; 0.24g slice 4x7mm with crust ; 1.13g sold 1.24g slice with crust ; 3.10g beautiful slice with crust ; 13g sold12x 7 mm ; 21x16 mm ; 2.5 gr 34 x 37 mm

Price: $190/gr

Ungrouped Achondrite from prev. Ureilite - NWA 1500 - Prov. the first basaltic ureilite!

New analysis suggest that this highy interesting achondrite could be brachinite related and probably originated from the Winona group parent body and may not come as originally thought from the Ureilite parent body.

Studied by: Frank Wlotzka, B.Clayton, R. Bartoschewitz, Goodrich

thin slices $155/g; endpieces with crust $150/g

NWA 3077 - AURE almost diamond free

1 piece partly covered with fresh fusion crust of 11.213g was found early 2003 in the Occidental Sahara

rare Ureilite type; thin part slice with/without crust. Let us kindly know which price/size range you might be interested in!

0,3g; 1,01g; Price BB $22

Shisr 007 - Ureilite

Total recovered mass: 9.024 kg. Classification: Typical texture of coarse (1-3 mm),

equigranular olivine (cores Fa 19.4, Cr2O3 0.55%)

pigeonite (Fs 17.4, Wo 9.0, Cr2O3 1.2%).

Classified by F. Wlotzka, Max-Planck-Inst. fur Chemie Dep.:Bartoschewitz

thin slices and segments: 1.9g; 2.4g; 3.8g Price