Melanterite
Encyclopedia
Melanterite is a mineral form of hydrous iron(II) sulfate
: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite
. It alters to siderotil
by loss of water
. It is a secondary sulfate mineral
which forms from the oxidation of primary sulfide mineral
s such as pyrite
and marcasite
in the near-surface environment. It often occurs as a post mine encrustation on old underground mine surfaces. It also occurs in coal
and lignite
seams exposed to humid air.
It also occurs as a rare sublimate phase around volcanic fumaroles. Associated minerals include pisanite, chalcanthite
, epsomite
, pickeringite, halotrichite
and other sulfate minerals.
It was first described in 1850.
Iron(II) sulfate
Iron sulfate or ferrous sulfate is the chemical compound with the formula FeSO4. Known since ancient times as copperas and as green vitriol, the blue-green heptahydrate is the most common form of this material...
: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite
Chalcanthite
Chalcanthite, whose name derives from the Greek, chalkos and anthos, meaning copper flower, is a richly-colored blue/green water-soluble sulfate mineral CuSO4·5H2O. It is commonly found in the late-stage oxidation zones of copper deposits...
. It alters to siderotil
Siderotil
Siderotil is an iron sulfate hydrate mineral with formula: FeSO4·5H2O which forms by the dehydration of melanterite. Copper commonly occurs substituting for iron in the structure. It typically occurs as fibrous or powdery encrustations, but may also occur as acicular triclinic crystals.It was...
by loss of water
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
. It is a secondary sulfate mineral
Sulfate mineral
The sulfate minerals are a class of minerals which include the sulfate ion within their structure. The sulfate minerals occur commonly in primary evaporite depositional environments, as gangue minerals in hydrothermal veins and as secondary minerals in the oxidizing zone of sulfide mineral deposits...
which forms from the oxidation of primary sulfide mineral
Sulfide mineral
The sulfide minerals are a class of minerals containing sulfide as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, the sulfarsenides and the sulfosalts...
s such as pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
and marcasite
Marcasite
The mineral marcasite, sometimes called white iron pyrite, is iron sulfide with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Both structures do have in common that they contain the disulfide...
in the near-surface environment. It often occurs as a post mine encrustation on old underground mine surfaces. It also occurs in coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
and lignite
Lignite
Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...
seams exposed to humid air.
It also occurs as a rare sublimate phase around volcanic fumaroles. Associated minerals include pisanite, chalcanthite
Chalcanthite
Chalcanthite, whose name derives from the Greek, chalkos and anthos, meaning copper flower, is a richly-colored blue/green water-soluble sulfate mineral CuSO4·5H2O. It is commonly found in the late-stage oxidation zones of copper deposits...
, epsomite
Epsomite
Epsomite is a hydrous magnesium sulfate mineral with formula MgSO4·7H2O or simply MgSO4. Epsomite forms as encrustations or efflorescences on limestone cavern walls and mine timbers and walls, as a volcanic fumaroles, and as rare beds in evaporate layers...
, pickeringite, halotrichite
Halotrichite
Halotrichite, also known as feather alum, is a highly hydrated sulfate of aluminium and iron. It is formed by the weathering and decomposition of pyrite commonly near or in volcanic vents. Its chemical formula is FeAl24·22H2O. It forms fibrous monoclinic crystals. The crystals are water...
and other sulfate minerals.
It was first described in 1850.