The humite groupGaines et al (1997) Dana's New Mineralogy Eighth Edition, Wiley is a group of

nesosilicate Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...

s with the general formula . When A is predominantly

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

we have the humite subgroup: *

norbergite Norbergite is a nesosilicate mineral with formula Mg3( Si O4)( F, OH)2. It is a member of the humite group. It was first described in 1926 for an occurrence in the Östanmoss iron mine in Norberg, Västmanland, Sweden, for which it is named. ...

, *

chondrodite Chondrodite is a nesosilicate mineral with formula . Although it is a fairly rare mineral, it is the most frequently encountered member of the humite group of minerals. It is formed in hydrothermal deposits from locally metamorphosed dolomite. I ...

, *

humite Humite is a mineral found in the volcanically ejected masses of Vesuvius Mount Vesuvius ( ; it, Vesuvio ; nap, 'O Vesuvio , also or ; la, Vesuvius , also , or ) is a somma-stratovolcano located on the Gulf of Naples in Campania, Ital ...

, *

clinohumite Clinohumite is an uncommon member of the humite group, a magnesium silicate according to the chemical formula ( Mg, Fe)9( Si O4)4( F,O H)2. The formula can be thought of as four olivine (Mg2SiO4), plus one brucite (Mg(OH)2). Indeed, the mineral ...

, 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 ...

-humite subgroup has members *

alleghanyite Alleghanyite is a moderately rare humite mineral with formula Mn5(SiO4)2(OH)2, belonging to the nesosilicates class. In general its occurrences are related with metamorphic (metamorphosed) manganese deposits. The mineral is named after Alleghany ...

, * manganhumite, *

sonolite Sonolite is a mineral with formula Mn9(SiO4)4(OH,F)2. The mineral was discovered in 1960 in the Sono mine in Kyoto Prefecture, Japan. In 1963, it was identified as a new mineral and named after the Sono mine. Description Sonolite is transparent ...

, and the leucophoenicite subgroup has members * ribbeite, *

leucophoenicite Leucophoenicite is a mineral with formula Mn7(SiO4)3(OH)2. Generally brown to red or pink in color, the mineral gets its name from the Greek words meaning "pale purple-red". Leucophoenicite was discovered in New Jersey, US and identified as a new ...

, *

jerrygibbsite Jerrygibbsite is a rare silicate mineral with the chemical formula . Jerrygibbsite was originally discovered by Pete J. Dunn in 1984, who named it after mineralogist Gerald V. Gibbs (born 1929). It has only been reported from the type locality ...

Chondrodite is the most common member of the humite group. It may contain Ti up to 9.6% . Chondrodite from

Sterling Hill Mine The Sterling Hill Mine, now known as the Sterling Hill Mine Tour & Museum of Fluorescence, is a former iron and zinc mine in Ogdensburg, Sussex County, New Jersey, United States. It was the last working underground mine in New Jersey when it c ...

and Franklin Mine contains

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

to 11.5% ZnO and Mn to 36% MnO, and grades to alleghanyite. The humite minerals commonly alter to serpentine or Mg-rich chlorite and dissolve by

weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement) ...

, leaving iron oxide residues.Phillips, W R and Griffen, D T (1981) Optical Mineralogy, pages 142 to 144

References

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