View a list of potential mercury meteorites

 You are on Cumulate Eucrite Page    

 Go To: Homepage  


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

cumulate eucrites  Cumulate eucrites are a scientifically highly interesting meteorite group. Cumulate eucrites are mostly coarse grained and have usually a wide range in bulk element composition due to compositional differences in their mineralogy.  Cumulate eucrites are basically gabbros composed of low-Ca pyroxene and calcic plagioclase. They also usually contain minor inclusions of silica,.troilite,  phosphate, chromite,  ilmenite, free metal. Several representatives of this group are unbrecciated: like Binda, ALH 85001 . Unbrecciated cumulate eucrites do have only  a low percentage of Ni, with <0.5 wt % Ni in the free metal inclusions. Binda, e.g. is a polymict breccia (Garcia, Prinz 1978) . Several polymict eucrites display also cumulate eucrite material. The texture of unbrecciated cumulate eucrites is equigranular with spyroxene and plagioclase grains 0.5-3 mm diameter (Hess and Henderson 1949, Lovering 1975, Mittlefehldt and Lindstrom.)

The original igneous pyroxene of cumulate eucrites was pigeonite, which has subsequently undergone subsolidus exsolution of augite and, in some cases, inversion to orthopyroxene, with additional augite exsolution. Hess and Henderson (1949) determined that original pigeonite in Moore County had only partially inverted to orthopyroxene: They described four pyroxenes in Moore County; low-Ca pigeonite developed from the original igneous pigeonite by exsolution of coarse lamellae of augite, and hypersthene developed from the low-Ca pigeonite through inversion and exsolution of fine lamellae of pyroxene phases. Harlow et al. (1979) found that the original igneous pigeonite in Serra de Mage had inverted to hypersthene, with development of four types of augite exsolution during the subsolidus cooling history. Similarly, in Moama the original igneous pigeonite has exsolved augite and inverted to hypersthene (Lovering 1975a Takeda et al. 1976). Binda is the most magnesian of the cumulate eucrites, and the only one classified by Delaney et al. (1984) as an orthopyroxene-cumulate eucrite. Takeda al. (1976) have shown that the original pyroxene in Binda was a low-Ca pigeonite that exsolved augite and inverted to hypersthene. Table 30 gives representative pyroxene analyses for selected cumulate eucrites, and estimated primary pigeonite compositions are plotted in Figure 42. As is the case for all HED meteorites, plagioclase in cumulate eucrites is calcic is on average more calcic than that in basaltic eucrites. Basaltic eucrite plagioclase has compositions in the range of bytownite to anorthite, while in cumulate eucrites the plagioclase is anorthite, An91-95;. A-881394 contains unusually calcic plagioclase, An,, {Takeda et al. 1997b). The K2O contents of cumulate eucrite plagioclases are very low typically <0.1 wt %.

The blue-metallic ilmenite occurs as small grains in most cumulate eucrites . Only in Moama ilmenite could not be found (Delaney et al. ,1984).

The composition of metal in the cumulate eucrites Binda, Moama, Moore County has received only cursory study (Duke 1965, Lovering 1964, 1975).

Based on modal abundances (Delaney et al 1984) cumulate eucrites can be divided into 2 subgroups:

a) feldspathic cumulate eucrites

b) orthopyroxene cumulate eucrites

There is a small but reasonable  possibility that  this meteorite might have originated Mercury

Anom. Eucrite with Mesosiderite tendency Dho 007

Black impact melt veins and pockets are abundant.

   Thermal history: Metal phases underwent a very slow cooling! (Yamaguchi et al)

This rare type is a cumulate eucrite, - a monomict breccia derived from a magmaticrock having a gabbroic texture consisting of subhedral grains of pyroxene

and plagioclase. Accessory minerals include metal, troilite, and chromite.

Dho 007 has a variety of glass inclusions (approximately up to 10 microns in diameter) contained in plagioclase  and pyroxene  grains as well as in the form a homogeneous melt. Gas bubbles formed from shrinkage during cooling can be found in the glass. The glass inclusions occur generally in round shape.

 Highly-silicic glass inclusions in Dho 007 and diogenites

The glass inclusions in Dho 007 have highly silicic compositions and are

 depleted in alkalis as compared with those in other meteorites.

Although silicate melts can be produced by low-degree partial melting of peridotites,

the resultant melts have not highly silicic composition but only basaltic, and

contain a high concentration of incompatible elements (Kushiro, +31/; Baker et al., +33/).

The inclusions analyzed in the present study are almost pure silica and are not very rich in

incompatible elements. Thus, these inclusions appear to be produced by another

formation mechanism. Schiano et al. (+33/) suggest that silicic-rich glasses in the

Earth’s upper mantle could be generated from a very low degree of partial melting of

ma.c minerals. A dehydrogenation of nominally anhydrous ma.c minerals by heating

or depressurization has also been proposed as a possible formation mechanism .

 However, in contrast to the results reported here, formation of silica-rich

melts in clinopyroxene-bearing rocks by both mechanisms should be accompanied by

enrichments of alkali and incompatible elements. In addition, a highly silicic melt

 should react with olivine during the migration of melt, so the formation

of the present inclusions requires generation in an olivine-absent system.

A highly silicic melt can be produced in the early stages of incongruent melting of

clinopyroxene, as estimated from melting experiments of clinopyroxene . In addition, the melt generated from orthopyroxene

is expected to be lower in contents of incompatible elements than that produced from

clinopyroxene-bearing rocks such as basalt, because of low abundances of incompatible

elements in orthopyroxene as compared with clinopyroxene.

Therefore, our results are consistent with a silica-rich melt generated from the incongruent melting of olivineabsent

orthopyroxenite. For Dhofar 007, formation of the inclusions in host plagioclase

might be considered by capturing incongruent melts of orthopyroxenite from

insights into their major compositions. It remains unclear if the melting event that

formed these secondary inclusions resulted from thermal heating or from shock-induced breakdown of pyroxene.

Based on the above evidence from these inclusions, they cannot have originated

from a late stage residual melt on the parent body. 

The occurrence of these secondary glass inclusions, outlining healed fractures in a single crystal, suggests migration of melts

after the crystallization process. Although the migration of highly silicic melts generally

is considered to be di$cult because of high viscosity, the viscosity of the original

melts of the glass inclusions analyzed might have decreased because of the enrichment

in sulphur.

Consideration of the data reported above allows an interpretation of the possible

petrogenesis of these glass inclusions. First, silica-rich melt penetrated into fractures in

the host mineral. Later annealing healed the fracture and tiny droplet glass inclusions

remained. Then, the daughter minerals precipitated from the inclusion melt during

cooling, and, finally, the remaining silicic melt solidifed. By this time, the glass

inclusions were modifed to the shape of negative crystals, which were elongated along

the cleavage direction of the host mineral orthopyroxene.

Ref.: Kouhei Kitazato+ and Masanori Kurosawa

+ Department of Earth and Planetary Science, University of Tokyo,

Hongo, Bunkyo-ku, Tokyo ++--**--

, Department of Planetary Science, Institute of Space and Astronautical Science,

Japan Aerospace Exploration Agency, Yoshinodai, Sagamihara ,,3-2/+*

- Institute of Geoscience, University of Tsukuba, Tennodai, Tsukuba -*/-2/1+

Ask for availibility + best price

Email your request or question 

Order Form



DaG 995 - very unusual eucrite, partly cumulated, fresh like a Fall!! 

Found 2001 January 3

Achondrite (eucrite)

 A single stone of 56.12 g partly covered by fusion crust was found 2001 January 3 by an anonymous finder in the sand desert of Dar al Gani. Classification and mineralogy (A. Greshake and M. Kurz): has subophitic texture with plagioclase laths embedded in exsolved Ca-pyroxene, augite, and silica; several areas of the meteorite are recrystallized; plagioclase, An89.5 (range An88.4-90.6); exsolved Ca-pyroxene with pigeonite lamellae, Fs51.8-60Wo5-15.2 and augite lamellae, Fs31-34.2Wo37.3-40.5; unexsolved augite Fs30.7Wo40.6; minor phases include orthopyroxene, ilmenite and Ti-rich chromite; plagioclase contains small crystallographically orientated inclusions of augite, pigeonite, and silica; augite contains small plagioclase and Ti-rich chromite inclusions; the sample appears to be unbrecciated in thin section; low degree of shock; low degree of weathering. Main mass with anonymous finder; type specimen 11.6 g plus 1 PTS MNB.

0,2g sold; 1.2g slice sold; 1.231g slice 24x21mm $160; 3.67g endpiece with crust $430;

mostly with fresh sparling black crust

Available only through us!

Email your request or question 

Order Form 

Erich's Meteorite Sale  (since 1978)
 A-1193-Vienna, Austria,  P.O. Box 88
Phone or Voice Mail:++43 - 676-388-1888
Voice Mail from US: 1-888-884-9828
Fax International:++43 - 1-368-1888
(alternate:++43 - 676-388-1889) 
Fax from US: 1-888-884-9828
from Austria call : 0676-388-1888
from Austria fax: 01-368-1888

Of course we are IMCA member since its creation

All Specimens Subject To Prior Sale
We reserve the right to refuse to sell to
individuals or groups with giving reasons!

View payment modalities

Customer Comments & Validations

If you are happy with our shipment you can recommend your satisfaction to friends, lists or forums. Thank you very much!

Please download kindly certificates for meteorites you purchased from us from our download site:

Certificates - Echtheits-Zertifikate