Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water-sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the ...

This work identifies unknown crystals found encrusting the Marcellus Shale Formation at the Mapleton Quarry locality in Central Pennsylvania, over the course of a month. The outcrop has been exposed for sufficient time for there to be advanced chemical weathering, allowing for the presence of secondary minerals to form and changes in the composition of the surrounding water table and environmen...

The Mashhad ultramafic complex with a Permo-Triassic stratigraphic age is exposed at the NE of Binaloud Mountain and the SW to NW of Mashhad city. This area is mainly composed of mafic and ultramafic rocks, metamorphosed carbonate and pelitic rocks and granitoids in a NW- SE trend. Serpentinized amphibole-peridotites are the main types of ultramafic rocks in this area. Minerals in these rocks i...

specific elements (cr, al, ca, and si) and loss on ignition (loi) were used for semi-quantitative determination of the normative mineralogical composition of naturally occurring chromium ores in ophiolite complexes. by far the occurring ore minerals are complex both from the mineralogical and chemical viewpoints. the secondary minerals serpentine and cr-containing chlorite (kaemmererite) form n...

electron-probe microanalyses and scanning electron microscopy of chrornitites from some ultramafic members of neyriz ophiolite indicate that sulifides of platinum- group minerals (pgms) occur as solid inclusions in chromite grains. laurite with the general formula of (ru ,os ,lr ) s , and erlichmanite are the main identified sulfide phases. the pgms occur as 4 to 20 microns euhedral to rectangu...