These meteorites were found in the Saharan Desert in Northwest Africa, likely by nomads. In order to classify them it would be necessary to cut off a section for analysis. Although they are exceedingly rare when compared to terrestrial rocks, these are the most abundant type of meteorite and are referred to as “common chondrites.” H and L (designating the amount of metal contained) type chondrites have been already extensively studied. Composed largely of spherical grain-like silicate chondrules, these stone meteorites were likely once part of the crust of a large asteroid.
This specimen is 100% guaranteed to be a stony meteorite of the general class "chondrite" and almost certainly of the class "ordinary chondrite" and based on magnetic response is very high an "H" chondrite signifying high metal content with the other alternatives being H signifying high metal to LL signifying very low relative metal content.
All our specimens, of the same type, have been analyzed by our fellow researchers from the Applied Petrology Loboratory of the University of Alicante (Environment and Earth Sciences Department).
The sample is chondritic meteorite. Under petrography microscope, the sample shows chondrules and rarely chondrules fragments. The major silicate mineral is olivine, which represents the 55% of its mineralogical composition. The chondrules have variable texture, mainly as PO (porphyritic olivine) and BO (barred olivine), and in a minor proportion as POP (porphyritic olivine and pyroxene), C (cryptocrystaline and RP (radial pyroxene). Plagioclase crystals appear in interstitial position with olivine in the chondrules. Individual olivine grains are spatially well distributed and their grain size is up to 2 mm in diameter. Glassy matrix surrounding olivine grains and chondrules are observed. Shock effects are present as abundant cross-cutting cracks in the individual olivine
crystals. The opaque minerals represent the 17 % of the sample composed mostly of iron, iron-nickel alloy (kamacite and taenite) and in minor proportion of troilite and chromite.
The BSE images show that olivine is the most common phase. The chondrules have olivine (Ol), plagioclase (Pl) and glass material developed during the melt of the meteorite. Coexistence of native Fe and Fe-Ni alloys. Minor troilite and chromite appear. EDS analyses indicate olivine has high forsterite Fo=0.80, plagioclase is albite rich Xab = 0.80. The metallic minerals show kamacite, taenite, troilite and chromite compositions.
The mineral composition and texture of the analyzed material suggest is a chondritic meteorite
Mineralogy and textural properties of samples were studied on polished thin sections using transmitted and reflected light microscopy at LPA (UA) and UGR.
Photomicrographs were performed by using:
o Petrographic microscope: ZEISS Assioskop (LPA-UA).
o Digital camera: Photometrics CoolSNAPcf
o Image capture Software: RS ImageTM v.1.8.6
Samples (polished thin-sections) also were studied under scanning electron microscope (Research Technical Services – UA). Minerals were located and identified using BSE mode on Hitachi S3000N SEM coupled with an X-ray detector Bruker XFlash 3001 for microanalysis (EDS) and mapping.
Semi-quantitative EDS X-ray microanalysis was performed using EDS spot analysis with acquisition time 60s and maximum process time to achieve best resolu¬tion of peaks in spectra.
ANNEX II. REFERENCES
Norton, O.R., 2002. The Cambridge Encyclopedia of Meteorites. Cambridge University Press, 374p.
Analysed material: M-CO1
Requested by: Jurassic Dreams
Dr. I.F. Blanco-Quintero
Dr. D. Benavente
Dr. J.C. Cañaveras
Applied Petrology Laboratory (APPLIED PETROLOGY LABORATORY
Environment and Earth Sciences Department
UNIVERSITY OF ALICANTE)