The compositions of rocks and soils on Mars shown here have been superseded by the results presented in: Rieder, R., et al., 1997, The chemical composition of the Martian soil and rocks returned by the mobile Alpha Proton X-ray Spectrometer: Preliminary results from the X-ray mode, Science, 278: 1771-1774.

Mars Pathfinder

Analysis of Martian Samples by the Alpha Proton X-Ray Spectrometer: Preliminary Results
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:

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

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