The latter mineral, a sulphide of iron, has a shiny metallic lustre and was often mistaken for gold itself: it is the infamous fool's gold.
During primary sulphate assimilation in chloroplasts, sulphate is reduced via sulphite to the organic sulphide which is used for cysteine biosynthesis.
Although an amino acid acceptor of sulphide is necessary for sulphate assimilation, only little attention was paid to the regulation of S assimilation by carbon metabolites.
In situations where large amounts of sulfides are being oxidized in this way, an enormous amount of acidity is associated with the sulfate product.
In this paper, we show that the opaline silica and amorphous sulphides are precipitating mainly on filamentous microbes and biofilms, which form templates for both the metal-rich sinter and the suspended flocs.
The solids used include natural clays and minerals, metal oxides and sulfides , metal salts, and mixed metal oxides.
These pollutants include ozone, sulphides , nitrogen oxides, carbon monoxide, hydrocarbons, and sulphur oxides.
Most pure metals, when freshly cut to expose a new surface, are lustrous, but most lose this luster quickly by combining with oxygen, carbon dioxide or hydrogen sulfide to form oxides, carbonates or sulfides .
DOCs include all compounds of carbon except for its oxides, sulphides and metal carbonates if they are identifiable by chemical name.
The technique can identify iron-bearing phases (such as oxides, silicates, sulfides , sulfates, and carbonates), as well as the amount of iron in each phase and the presence of iron in various oxidation states.