Preliminary Mars Pathfinder APXS Results


Elemental Composition of Rocks and Soil

Element A-2, Soil A-4, Soil A-5, Soil A-3, Rock
"Barnacle Bill"
A-7, Rock
"Yogi"
weight % weight % weight % weight % weight %
C (Carbon) (note 2) - - - - -
O (Oxygen) (notes 2,3) 42.5 43.9 43.2 45.0 44.6
Na (Sodium) 3.2 3.8 2.6 3.1 1.9
Mg (Magnesium) 5.3 5.5 5.2 1.9 3.8
Al (Aluminum) 4.2 5.5 5.4 6.6 6.0
Si (Silicon) 21.6 20.2 20.5 25.7 23.8
P (Phosphorus) - 1.5 1.0 0.9 0.9
S (Sulfur) 1.7 2.5 2.2 0.9 1.7
Cl (Chlorine) - 0.6 0.6 0.5 0.6
K (Potassium) (note 4) 0.5 0.6 0.6 1.2 0.9
Ca (Calcium) 4.5 3.4 3.8 3.3 4.2
Ti (Titanium) 0.6 0.7 0.4 0.4 0.5
Cr (Chromium) 0.2 0.3 0.3 0.1 0.0
Mn (Manganese) (note 4) 0.4 0.4 0.5 0.7 0.4
Fe (Iron) 15.2 11.2 13.6 9.9 10.7
Ni (Nickel) - - 0.1 - -
Sum 100.0 100.0 100.0 100.0 100.0

Notes:
(1) Analysis based on X-ray data.
(2) Direct results on C and O will be available from the analysis of alpha spectra at a later date.
(3) O is calculated from oxide stoichiometry, assuming S in the form of SO3 and Fe in the form of FeO.
(4) Values for K and Mn are upper limits; more accurate numbers will be available after further analysis.


Oxides

Oxide A-2, Soil A-4, Soil A-5, Soil A-3, Rock
"Barnacle Bill"
A-7, Rock
"Yogi"
weight % weight % weight % weight % weight %
Na2O 4.3 5.1 3.6 4.2 2.5
MgO 8.7 9.0 8.6 3.1 6.3
Al2O3 8.0 10.4 10.1 12.4 11.4
SiO2 46.1 43.3 43.8 55.0 50.9
SO3 4.3 6.2 5.4 2.2 4.2
K2O 0.6 0.7 0.7 1.4 1.1
CaO 6.3 4.8 5.3 4.6 5.8
TiO2 1.1 1.1 0.7 0.7 0.8
MnO 0.5 0.5 0.6 0.9 0.5
FeO 19.5 14.5 17.5 12.7 13.8

Notes:
Analysis based on X-ray data.
Values for potassium and manganese are upper limits; more accurate numbers will be available after further analysis.
Minor elements such as phosphorus, chlorine and chromium are omitted from this table.


Comparison of oxides for Mars and Earth samples

Mars

Earth

Oxide A-3, Rock A-5, Soil SNCs Continental Crust Oceanic Crust
"Barnacle Bill" (Mars Meteorites) Average Sediments
weight % weight % weight % weight % weight % weight %
MgO 3.1 8.6 9.3 - 31.6 3.1 3.1 7.7
Al2O3 12.4 10.1 0.7 - 12.0 15.2 13.0 15.6
SiO2 55.0 43.8 38.2 - 52.7 60.2 50.0 50.7
K2O* 1.4 0.7 0.022 - 0.19 2.9 2.0 0.17
CaO 4.6 5.3 0.6 - 15.8 5.5 8.4 11.4
TiO2 0.7 0.7 0.1 - 1.8 0.7 0.7 1.5
MnO* 0.9 0.6 0.44 - 0.55 0.1 0.1 0.16
FeO 12.7 17.5 17.6 - 27.1 6.05 5.5 9.9
FeO/MnO 14.1 29.2 37.0 - 51.5 - - -

*Values for potassium (K) and manganese (Mn) are probably too high and subject to revision after further analysis.


* Mars Pathfinder APXS results page
* Mars Pathfinder science results page
* Mars Pathfinder home page at NSSDC


Author/Curator:
Dr. David R. Williams, dave.williams@nasa.gov
NSSDC, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771
+1-301-286-1258
[NSSDC Logo]
NASA Official: Ed Grayzeck, edwin.j.grayzeck@nasa.gov
Last Updated: 14 August 1997, DRW