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Science 1 October 1976:
Vol. 194. no. 4260, pp. 81 - 84
DOI: 10.1126/science.194.4260.81
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Articles

Preliminary Results from the Viking X-ray Fluorescence Experiment: The First Sample from Chryse Planitia, Mars

PRIESTLEY TOULMIN III 1, BENTON C. CLARK 2, A. K. BAIRD 3, KLAUS KEIL 4, and HARRY J. ROSE JR. 1

1 U.S. Geological Survey, Reston, Virginia 22092
2 Planetary Sciences Laboratory, Martin Marietta Aerospace, Denver, Colorado 80201
3 Department of Geology, Pomona College, Claremont, California 91711
4 Department of Geology and Institute of Meteoritics, University of New Mexico, Albuquerque 87131

Iron, calcium, aluminum, silicon, and sulfur are major elements in the first surface sample of Mars that has been analyzed by the Viking x-ray fluorescence spectrometer. Titanium is present in minor quantities. This is consistent with the sample being a mixture of fine silicate and oxide mineral grains, with a significant proportion of sulfates, possibly hydrated. Ferric oxide is regarded as the red pigmenting agent on the martian surface, but if it coats silicate grains, the coatings must be very thin (le 2 micrometers) or discontinuous. A high abundance of Fe, relatively low abundances of Al, Rb, Sr, and Zr, and a high Ca/K ratio are distinctive features of the spectra. Preliminary determinations indicate the following abundances (as percentages by weight): Fe, 14 ± 2; Ti < 1; S, 2 to 5; the Ca/K ratio by weight is greater than 5.

Submitted on September 2, 1976


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Inorganic Analyses of Martian Surface Samples at the Viking Landing Sites.
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Mineralogic and Petrologic Implications of Viking Geochemical Results From Mars: Interim Report.
A. K. Baird, A. K. BAIRD, P. TOULMIN III, B. C. CLARK, H. J. ROSE JR., K. KEIL, R. P. CHRISTIAN, and J. L. GOODING (1976)
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North Polar Region of Mars: Imaging Results from Viking 2.
J. A. Cutts, J. A. CUTTS, K. R. BLASIUS, G. A. BRIGGS, M. H. CARR, R. GREELEY, and H. MASURSKY (1976)
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Status of the Viking Missions.
G. A. Soffen and G. A. SOFFEN (1976)
Science 194, 57-59
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Search for Organic and Volatile Inorganic Compounds in Two Surface Samples from the Chryse Planitia Region of Mars.
K. Biemann, K. BIEMANN, J. ORO, P. TOULMIN III, L. E. ORGEL, A. O. NIER, D. M. ANDERSON, P. G. SIMMONDS, D. FLORY, A. V. DIAZ, et al. (1976)
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