DiagenesisDiagenesis (ˌdaɪ.əˈdʒɛnəsɪs) is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a role as sediments become buried much deeper in the Earth's crust. In the early stages, the transformation of poorly consolidated sediments into sedimentary rock (lithification) is simply accompanied by a reduction in porosity and water expulsion (clay sediments), while their main mineralogical assemblages remain unaltered.
TroiliteTroilite is a rare iron sulfide mineral with the simple formula of FeS. It is the iron-rich endmember of the pyrrhotite group. Pyrrhotite has the formula Fe(1-x)S (x = 0 to 0.2) which is iron deficient. As troilite lacks the iron deficiency which gives pyrrhotite its characteristic magnetism, troilite is non-magnetic. Troilite can be found as a native mineral on Earth but is more abundant in meteorites, in particular, those originating from the Moon and Mars.
DisulfideIn biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In biology, disulfide bridges formed between thiol groups in two cysteine residues are an important component of the secondary and tertiary structure of proteins. Persulfide usually refers to compounds. In inorganic chemistry disulfide usually refers to the corresponding anion S22− (−S−S−).
Acid mine drainageAcid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines or coal mines. Acid rock drainage occurs naturally within some environments as part of the rock weathering process but is exacerbated by large-scale earth disturbances characteristic of mining and other large construction activities, usually within rocks containing an abundance of sulfide minerals. Areas where the earth has been disturbed (e.g.
OxideAn oxide (ˈɒksaɪd) is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of –2) of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of (called a passivation layer) that protects the foil from further oxidation.
CinnabarCinnabar (ˈsɪnəˌbɑr; ), or cinnabarite (ˌsɪnəˈbɑraɪt), is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury and is the historic source for the brilliant red or scarlet pigment termed vermilion and associated red mercury pigments. Cinnabar generally occurs as a vein-filling mineral associated with recent volcanic activity and alkaline hot springs. The mineral resembles quartz in symmetry and in its exhibiting birefringence.
Iron sulfideIron sulfide or Iron sulphide can refer to range of chemical compounds composed of iron and sulfur. By increasing order of stability: Iron(II) sulfide, FeS Greigite, Fe3S4 (cubic) Pyrrhotite, Fe1−xS (where x = 0 to 0.2) (monoclinic or hexagonal) Troilite, FeS, the endmember of pyrrhotite (hexagonal) Mackinawite, Fe1+xS (where x = 0 to 0.1) (tetragonal) Marcasite, orthorhombic FeS2 Pyrite, cubic FeS2 (fool's gold) Arsenopyrite (mispickel), FeAsS, or Fe(As-S), Fe(III) mixed arseno-sulfide (monoclinic) Iron(II
Lattice constantA lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has only one lattice constant, the distance between atoms, but in general lattices in three dimensions have six lattice constants: the lengths a, b, and c of the three cell edges meeting at a vertex, and the angles α, β, and γ between those edges.
ThiosulfateThiosulfate (IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula . Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, e.g. sodium thiosulfate . Thiosulfate also refers to the esters of thiosulfuric acid, e.g. O,S-dimethyl thiosulfate . The prefix thio- indicates that the thiosulfate is a sulfate with one oxygen replaced by sulfur. Thiosulfate is tetrahedral at the central S atom.
ShaleShale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2Si2O5(OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by its tendency to split into thin layers (laminae) less than one centimeter in thickness. This property is called fissility. Shale is the most common sedimentary rock.
