A disadvantage of pressure oxidation is that any silver in the feed material will often react to form silver jarosite inside the autoclave, making it difficult and expensive to recover the silver.
32.
"' Jarosite "'is a basic hydrous sulfate of potassium and iron with a chemical formula of KFe 3 + 3 ( OH ) 6 ( SO 4 ) 2.
33.
In 2004 jarosite was detected on Mars by a M�ssbauer spectrometer on the MER-B rover, which has been interpreted as strong evidence that Mars once possessed large amounts of liquid water.
34.
Mysterious spheres of clay, 1.5 to 5 inches in diameter, covered with jarosite have recently been discovered beneath the Temple of the Feathered Serpent an ancient six level stepped pyramid 30 miles from Mexico City.
35.
In a finely layered rock, Opportunity detected concentrations of jarosite, an iron sulfate mineral that forms with water, as well as layers of salts that match evaporation sequences found on Earth when briny water pools dry up.
36.
Hydrothermal alteration of the central lava dome and iron-bearing deposits has generated alunite, anatase, chlorite, copper veinlets, gypsum, illite, jarosite, labradorite, quartz, rutile, sanidine, smectite, and sulfur.
37.
It occurs associated with thenardite, jarosite, sylvite and hematite in fumaroles; with blodite, syngenite, mirabilite, picromerite, borax and halite in evaporites; and with syngenite, whitlockite, monetite, niter and gypsum in guano deposits.
38.
Features that suggest this include cross-bedded sediments, the presence of many small spherical pebbles that appear to be concretions, vugs inside rocks, and the presence of large amounts of magnesium sulfate and other sulfate-rich minerals such as jarosite.
39.
The discovery of water-formed minerals on Mars including hematite and jarosite, by the Opportunity rover and goethite by the Spirit rover, has led to the conclusion that climatic conditions in the distant past allowed for free-flowing water on Mars.
40.
In the jarosite-natrojarosite series Na substitutes for K to at least Na / K = 1 : 2.4 but the pure sodium end member NaFe 3 + 3 ( SO 4 ) 2 ( OH ) 6 is not known in nature.
