Magnesium sulfate constituents of evaporitic potassium-magnesium (K-Mg) salts deposits. Bright spots observed by the Dawn Spacecraft in Occator Crater on the dwarf planet Ceres are most consistent with reflected light from magnesium sulfate hexahydrate. Almost all known mineralogical forms of MgSO are hydrates. Epsomite is the natural analogue of "Epsom salt". Another heptahydrate, the copper-containing mineral alpersite (Mg,Cu)SO·7HO, was recently recognized. Both are, however, not the highest known hydrates of MgSO, due to the recent terrestrial find of meridianiite, MgSO·11HO, which is thought to also occur on Mars. Hexahydrite is the next lower (6) hydrate. Three next lower hydrates—pentahydrite, starkeyite, and especially
Low valent magnesium compounds Low valent magnesium compounds A number of stable low valent magnesium compounds containing a metal-metal, Mg-Mg, bond, where magnesium exhibits the formal oxidation state of +1 are known. These compounds generally have the formula LMg, where L represents a bulky ligand. The first examples of these stable magnesium(I) compounds were reported in 2007. The chemistry of Mg is dominated by the +2 oxidation state and prior to 2007 only examples of crystalline compounds with short Mg-Mg distances that may indicate an Mg-Mg bond were known, such as the ternary metal hydrides MgRuH, MgRuH, and MgIrH and magnesium diboride, Calculations had