Manganvesuvianite is a rare mineral with formula . The mineral is red to nearly black in color. Discovered in South Africa and described in 2002, it was so named for the prevalence of
manganese
Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
in its composition and its relation to
vesuvianite
Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism. It was first discovered within ...
.
Occurrence and formation
Manganvesuvianite crystals occur as long prisms up to .Armbruster 2002, p. 138. Small crystals are transparent and red to lilac in color; large crystals are opaque and nearly black in color with dark-red internal reflections.Armbruster 2002, pp. 138–9. Strongly zoned crystals less than in size constitute rock-forming manganvesuvianite.Armbruster 2002, p. 139.
, manganvesuvianite has been found at two locations in South Africa. It formed at temperatures of by the
hydrothermal alteration
Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical co ...
of sedimentary and metamorphic manganese ores. Crystallization occurred in fault planes and lenticular bodies in the ore bed or by filling
veins
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
and
vug
A vug, vugh, or vugg (
) is a small- to medium-sized cavity inside rock. It may be formed through a variety of processes. Most commonly, cracks and fissures opened by tectonic activity (folding and faulting) are partially filled by quartz, ...
s. Manganvesuvianite has been found in association with calcite, manganese-poor
grossular
Grossular is a calcium-aluminium species of the garnet group of minerals. It has the chemical formula of Ca3Al2(SiO4)3 but the calcium may, in part, be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from t ...
serandite
Serandite is a mineral with formula Na(Mn2+,Ca)2Si3O8(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Serandite is generally red, brown, black or colorless. The correct name lacks an accent.
Description
Serandite i ...
-
pectolite
Pectolite is a white to gray mineral, Na Ca2 Si3 O8(O H), sodium calcium hydroxide inosilicate. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a specif ...
xonotlite
Xonotlite, or eakleite, is a mineral of general formula named by the German mineralogist Karl Friedrich August Rammelsberg in 1866. The name originates from its discovery locality, Tetela de Xonotla, Puebla, Mexico. Although it was discovered i ...
.Armbruster 2002, pp. 139–40.
Manganvesuvianite is a member of the vesuvianite group and is the
manganese
Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
analogue of vesuvianite.
History
In 1883, Arnold von Lasaulx made the first detailed description of vesuvianite containing up to 3.2 wt%MnO from
Lower Silesia
Lower Silesia ( pl, Dolny Śląsk; cz, Dolní Slezsko; german: Niederschlesien; szl, Dolny Ślōnsk; hsb, Delnja Šleska; dsb, Dolna Šlazyńska; Silesian German: ''Niederschläsing''; la, Silesia Inferior) is the northwestern part of the ...
in Poland.Armbruster 2000, p. 571. Studies in the 1980s and 1990s revealed that the vesuvianite group was more complex than previously assumed, necessitating the definition of new minerals. In 2000, vesuvianite was found containing up to 14.3 wt% MnO from the Kalahari manganese fields of
Northern Cape Province
The Northern Cape is the largest and most sparsely populated province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley. It includes the Kalahari Gemsbok National Park, part of the Kgalagadi ...
, South Africa.Armbruster 2000, p. 570. Manganvesuvianite proper was discovered in the Wessels () and N'Chwaning (shaft II; ) mines of the Kalahari manganese fields and described in 2002 in the journal ''Mineralogical Magazine''. It was named ''manganvesuvianite'' for the significant manganese in its formula and its relation to vesuvianite. The mineral and name were approved by the IMA Commission on New Minerals and Mineral Names (IMA 2000-40).Armbruster 2002, p. 137. The
type specimen
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...