Eberswalde, craters in Margaritifer Terra, are thought to have formerly held lakes because they contain deltas and iron / magnesium smectite minerals which need water to form.
32.
Greensands are green because of iron-bearing glauconite which is usually recognized as illite / mica or mixed layer illite-smectite clay by x-ray diffraction.
33.
Smectite clays ( trioctahedral ) that are formed in the presence of water were found by Curiosity in sedimentary rocks ( mudstones ) at Yellowknife Bay in Gale crater.
34.
Launched in 2005 this orbiter carried multiple instruments which found the mineralogy to be dominated by mafic minerals such as olivine, mica, pyroxene and smectite clays such as kaolinite.
35.
Their preferred soils have a much higher cation-exchange capacity than the adjacent layers of soils that were rejected because they are rich in the minerals smectite, kaolin and mica.
36.
Using instruments on the Mars Reconnaissance Orbiter they found the minerals smectite, silica, zeolite, serpentine, carbonate, and chorite that are common in impact-induced hydrothermal systems on Earth.
37.
Comparing soils along a gradient towards progressively cooler or drier climates, the proportion of kaolinite decreases, while the proportion of other clay minerals such as illite ( in cooler climates ) or smectite ( in drier climates ) increases.
38.
Montmorillonite is a subclass of smectite, a 2 : 1 phyllosilicate mineral characterized as having greater than 50 % octahedral charge; its cation exchange capacity is due to isomorphous substitution of Mg for Al in the central alumina plane.
39.
In December 2008, NASA's Mars Reconnaissance Orbiter found that rocks at Nili Fossae contain carbonate minerals, a MRO are aluminum smectite, iron / magnesium smecite, hydrated silica, kaolinite group minerals, and iron oxides.
40.
The soil is typically 3 to 5 inches of high shrink-swell clay topsoil ( smectite clay; hard, cloddy when dry ) over several inches of subsoil enriched in precipitated gypsum and salts ( powdery when dry ).
