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Mafic Minerals in Nili Fossae
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Mafic Minerals in Nili Fossae

Acquired Date: August 13, 2009
Release Date: June 27, 2014
Latitude: 23.12 N
Longitude: 76.89 E
Keywords: Crater Interior/Rim/Ejecta, Fracture/Faults, Hydrated Mineral, Mafic minerals, Phyllosilicate minerals, Dichotomy Boundary
Parameters: D2300 (Fe-Mg phyllosilicates), LCPINDEX2 (Low-Calcium Pyroxene), OLINDEX3 (Olivine)

The vast majority of the planetís crust is unaltered igneous rock although there are some occurrences of aqueously altered rocks linked to past water activity. The colors here show concentrations of different minerals common in rocks that might tell us about processes that happened in Marsí past. The green/cyan color denotes a variety of a mineral called pyroxene that has an unusually low content of calcium (low-calcium pyroxene, or LCP). Pyroxene is the dominant silicate mineral in most igneous rocks and contains iron, magnesium, and variable amounts of calcium as well as silicon and oxygen. Rocks rich in the iron-magnesium silicate mineral olivine appear red and rocks altered by water, called phyllosilicates, are shown in blue/purple.



The vast majority of the planetís crust is unaltered igneous rock although there are some occurrences of aqueously altered rocks linked to past water activity. The colors here show concentrations of different minerals common in rocks that might tell us about processes that happened in Marsí past. The green/cyan color denotes a variety of a mineral called pyroxene that has an unusually low content of calcium (low-calcium pyroxene, or LCP). Pyroxene is the dominant silicate mineral in most igneous rocks and contains iron, magnesium, and variable amounts of calcium as well as silicon and oxygen. Rocks rich in the iron-magnesium silicate mineral olivine appear red and rocks altered by water, called phyllosilicates, are shown in blue/purple.

Phyllosilicates are clay and clay-like minerals formed by chemical reactions with liquid water. Their microscopic crystal form in very thin stacked layers and are also called sheet silicates. The phyllosilicates here are rich in iron and magnesium. This composition of phyllosilicate is most common in the southern highlands, and is thought to consist of minerals formed by reaction of igneous basaltic rocks with water, without flushing of soluble elements.

Link to further description of the spectral parameters shown in this image can be found here.

Disclaimer: Colors shown here represent indicators of mineralogy and are not what the human eye would see.

Acknowledgements: THEMIS, MOLA, CRISM, Google Earth.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument also tracks seasonal variations in dust and ice aerosols in the Martian atmosphere, and water content in surface materials — leading to new understanding of the climate.

Credit: NASA/JPL/JHUAPL

   

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