Palagonite

Palagonite is an alteration product from the interaction of water with

Galapagos Islands. Charles Darwin recognized the origin of these cones during his visit to the islands. Palagonite can also be formed by a slower weathering

of lava into palagonite, resulting in a thin, yellow-orange rind on the surface of the rock. The process of conversion of lava to palagonite is called palagonitization.

Palagonite soil is a light yellow-orange dust, comprising a mixture of particles ranging down to sub-micrometer sizes, usually found mixed with larger fragments of lava. The color is indicative of the presence of iron in the +3 oxidation state, embedded in an amorphous matrix.

Palagonite tuff is a tuff composed of sideromelane fragments and coarser pieces of basaltic rock, embedded in a palagonite matrix. A composite of sideromelane aggregate in palagonite matrix is called hyaloclastite.

On Mars

Based on infrared spectroscopy, the fine-grained component of Mauna-Kea palagonite is the terrestrial material with the best match to the spectral properties of Martian dust, and is believed to be similar in composition and in origin to dusty component of the surface regolith of Mars.^[1]^[2] The palagonitic tephra from a cinder cone in Hawaii has been used to create Martian regolith simulant for researchers.^[3] The spectroscopic signature of palagonitic alteration on Mars is used as evidence for the existence of water on Mars.

References

^ R.B. Singer, "Mineralogy of High-Albedo Soils and Dust on Mars", AGU paper 2B1214, J. Geophys. Res. 10, 159-10,168, 1982; also R. B. Singer and T. L. Roush, "Spectral reflectance properties of particulate weathered coatings on rocks: Laboratory modeling and applicability to Mars", in Lunar Plan. Sci. Conf. XIV, 708-709, 1983.
^ E.A. Guinness,R. E. Arvidson, M. A. Dale-Bannister, R. B. Singer and E. A. Brukenthal, "On the Spectral Reflectance Properties of Materials Exposed at the Viking Landing Sites", Proc. 17th Lunar and Planetary Science Conf., Part 2, J. Geophys. Res. 92, E575-E587, 1987.
^ Allen, C. C.; Morris, R. V.; Lindstrom, D. J.; Lindstrom, M. M.; Lockwood, J. P. (March 1997). JSC Mars-1: Martian regolith simulant (PDF). Lunar and Planetary Exploration XXVIII. Archived from the original (PDF) on 10 September 2014. Retrieved 10 May 2014.

v t e Types of basalts
Basalts by tectonic setting	Flood basalt Mid-ocean ridge basalt Ocean island basalt Volcanic arc basalt
Basalts by form and flow	Columnar basalt Pillow basalt Aa lava Pahoehoe lava
Basalts by chemistry	Tholeiitic basalt Calc-alkaline basalt Alkali basalt Trachybasalt Hawaiite Mugearite Picrite basalt
Important minerals	Olivine Pyroxene Plagioclase Amphibole Magnetite Ilmenite Quartz Cristobalite Tridymite
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On Mars

References

Further reading