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Preliminary Raman spectroscopic survey on

a Martian meteorite - Los Angeles

The primary task of this survey is to identify the main mineral phases of the meteorite as well as accessory phases, even though they might be terrestrial alteration or contaminants. We observe Raman spectra of crystalline quartz and feldspar in addition to their glassy equivalents. Spectra of hematite and goethite suggest alteration of Fe-Ti oxides. Accessory or contaminant phases include hydroxyapatite, hydroxy-chlorapatite, graphitic carbon, calcite, SiC, and hydrocarbon compounds, including metalloporphyrin and paraffin.

A. Studied rock chip -- from stone #2

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side 1 side 2

B. Mineral phases identified -- Most of the Raman spectra were obtained on the A side of the rock chip, mainly by spot reconnaissance [5], but also by linear and grid point-counting measurements [6]. Table 1 lists the major and minor mineral phases identified by the Raman survey, as well as chemical characteristics determined from a limited number of spectra. The results of a petrologic and mineralogical study of this meteorite reported previously [1,4] are listed in table 1 for comparison. A good correspondence exists between this Raman survey on a rough sawn rock slab and the results of [1] from thin sections in identification of the main mineral phases. Phases not reported previously but identified by the Raman survey are listed in red in table 1

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By Raman spec. By A.E. Rubin et al.
pyroxene Mg/(Mg+Fe+Ca) 0.481-0.302 augite & pigeonite
Ca/(Mg+Fe+Ca) 0.161-0.221
hedenbergite hedenbergite
olivine Mg/(Mg+Fe) <0.06 fayallite
glasses & related SiO2 glass silica galss
feldspar galss K-rich feld glass
crystalline Qtz maskelynite
crystalline feld. K-Si rich feld melt
opaques ilmenite ilmenite
ulvospinel comp.vari. ulvospinel
pyrrhotite comp.vari. pyrrhotite
hematite
goethite
phosphates merrillite merrillite
chloapatite comp.vari. chloapatite
hydroapatite hydroapatite
chlohydroapatite
others carbon
calcite
metalloporphyrin B side only
paraffine terr. conta.
SiC terr. conta.

C. terrestrial contaminates -- Raman detection of organic phases of biogenesis

Reference:  Rubin et al., abstract #1963 for 31th LPSc (2000)

Wang A., Kuebler, K.E., Freeman J., Jolliff B. L., Preliminary Raman spectroscopic survey on a martian meteorite Los Angeles, 32th LPSC, 2001.

                   

 

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