Glauconite


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Related to Glauconite: Glaucophane, glauconitic sandstone

glauconite

[′glȯ·kə‚nīt]
(mineralogy)
K15(Fe,Mg,Al)4-6(Si,Al)8O20(OH)4 A type of clay mineral; it is dioctohedral and occurs in flakes and as pigmentary material.

Glauconite

 

a mineral, hydrated iron aluminosilicate belonging to the hydromica group. It is characterized by variable and complex chemical composition; its main components are silica (49-56 percent), ferrous and ferric oxides (up to 21 percent), aluminum oxide (up to 18 percent), potassium oxide (up to 10 percent), magnesium oxide (up to 7 percent), and water (up to 13 percent). It crystallizes in the monoclinic system.

The color of glauconite is green (from dark green, almost black, to olive green). Its hardness on the mineralogical scale is 2-3, and its density is 2,200-2,300 kg/m3. Its capacity for absorbing water, as well as for ion exchange, is considerable. It is found among sedimentary rocks as round grains of cryp-tocrystalline structure, less frequently as small crystals of roughly hexagonal shape. It is formed at the bottom of the sea, where it settles as a gel. Cases of the formation of glauconite through the substitution of grains of biotite and other minerals in marine ooze are known. Glauconite is widespread in sedimentary rocks of various ages, mainly Mesozoic and Cenozoic.

Because of its capacity for cation exchange, glauconite is used to soften water and, since it contains a considerable amount of potassium oxide, as a soil fertilizer. It is also used for making green paint.

References in periodicals archive ?
Chemical compositions of glauconite through the Teegulines Clay from the AUB1010 borehole were reported in the [M.sup.+]x[(Si/4).sup.-1] versus [sup.VI]Fe(II + III)/[[summation].sup.VI] cations diagram (Figure 3(g)).
Maturation from nascent glauconite (glauconitic smectite) to highly evolved glauconite is related to a decrease in Al, Si, Mg, Ca and Na and an increase in K and Fe, producing a decreasingly expandable smectitic component (e.g., Odin and Matter, 1981; Amorosi, 1995; Eder et al., 2007; Sanchez-Navas et al., 2008).
Accessory minerals include biotite, muscovite, zircon, tourmaline, apatite, titanite, detrital calcite and detrital glauconite. Biotite phyllite, quartz muscovite schist, quartzite, chert, limestone, and sandstone fragments are present.
The rock contains accessory amounts of zircon, tourmaline, garnet, rutile, calcopyrite and glauconite, whereas corundum, amphiboles and disthen have been preserved in Western Estonia [22].
Absence of glauconite, bioturbation and sand grains but the presence of herringbone cross stratification in dolomite suggests intratidal to supratidal environment of deposition.
The nuclei of the phosphatic intraclasts may include shell fragments, detrital quartz, and glauconite grains.
The residues were sorted to 850 microns, with the high quantity of glauconite and ferruginous grains preventing sorting of finer fractions.
Aptly nicknamed the blue earth, this sand contains high levels of a mineral known as glauconite, a silicate that is responsible for its unusual blue-green color.
Sand is usually of whitish colour, which mainly depends on the amount of quartz and feldspar in it; other colours are determined by the additives like glauconite, which gives green colour, ferrous oxides and hydroxide layer, which give yellow, brown and pinkish colours, organic carbon-rich materials add grey and blackish colour.
Structural characterization and application of an analogue of the mica mineral Glauconite as a sorbent for the heavy metal ions [Cd.sup.2+], [Hg.sup.2+] & [Pb.sup.2+].
A remarkable number of other species have also been identified as inclusions in Zambian emeralds, including actinolite, tremolite, chlorite, dravite, apatite-(CaF), magnetite, hematite, quartz, fluorite, magnesite, siderite, dolomite, calcite, ankerite, niobium-rich rutile, pyrite, talc, zircon, barite, albite, lepidocrocite, glauconite, quartz, chrysoberyl, margarite, muscovite, biotite, brookite, tourmaline and chrysotile (Huong, 2008; Zwaan et al., 2005; Milisenda et al., 1999; Moroz and Eliezri, 1999; Graziani et al., 1983; Koivula, 1982, 1984; Gubelin and Koivula, 1986).