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A soft mica having a green hue and a high iron content.
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Celadonite is widely documented as a product of low temperature alteration of basalt [9] and is also predicted to form in the model at temperatures between 2 and 170[degrees]C, where it coprecipitates with dolomite.
Nevertheless, the 003 peak is slightly asymmetric, with a small shoulder towards lower 20[theta] angles and close to 35 [degrees]2[theta] showing two peaks, which is typical of celadonite (Odin and Matter, 1981).
The vesicles and fractures in basalts were gradually filled up with secondary minerals, developing amygdales and veins usually showing mineral zoning distribution though, in some cases, they were not completely filled Figure 5a gives an example of the occurrence of a mixed layer of celadonite (Fe-rich mica) and non-tronite (Fe-rich smectite) and vesicles commonly lined by these mineral phases Celadonite is usually green and botroidal and has fibrous spheroidal morphology, having detectable striated birefringence under crossed nicols Nontronite is typically brown in transmitted light and does not have a discernable structure except for banding parallel to the cavity wall It occasionally exhibits geopetal features.
The original ash color from the volcanoes is tan; the other colors come from minerals in the various deposits - red from iron oxides, blue from celadonite, yellow from zeolite - with some of the colored layers becoming shifted or combined through millions of years of erosion.
Celadonite, [([R.sup.2+].sub.1.0][[R.sup.3+].sub.1.0]).sup.VI][([Si.sub.4]).sup.IV] [O.sub.10][(OH).sub.2]K, contains more AlMg than [Fe.sup.3+] > [Fe.sup.2+] in the octahedral sheet.
One of the most distinguishing features of the Laguna agate is the presence of blue-green celadonite as a coating on the exterior of most of the nodules.
Basaltic rocks react with oxygenated deep-sea water to form secondary hydrous alteration minerals, including a variety of Fe-oxyhydroxides and micas, and clay minerals such as celadonite (K(Mg,Fe)(Fe,Al)[Si.sub.4][O.sub.10][(OH).sub.2]) and smectite (e.g., montmorillinite, (1/2Ca,Na)[(Al,Mg,Fe).sub.4] [(Si,Al).sub.8][O.sub.20][(OH).sub.4]*[nH.sub.2]O)(Honnorez, 1981; Alt, 1995).
The dominant vesicle fillings in basalt are celadonite and silica minerals, with minor "heulandite", chabazite, and analcime.
In case of some naturally occuring true micas (polylithionite, tainiolite and celadonite) [Si.sup.4+] practically fills completely the tetrahedral positions, while in the majority of common mica species (muscovite, phlogopite) [Al.sup.3+] replaces [Si.sup.4+] in the ratio 1:3.
Sabina (1994) has also reported a mineral related to glauconite, or perhaps celadonite, in the sill rock.
Mineralogists of the 19th century were much more successful in the description of new layer hydrosilicates: allophane, amesite, antigorite, aspidolite, batavite, biotite /a series name/, celadonite, chamosite, chrysotile /a series name/, clinochlore, corundophyllite, cronstedtite, delessite, diabantite, ephesite, glauconite /a series name/, halloysite, kaolinite, muscovite, nacrite /a polytype/, nontronite, palygorskite, paragonite, penninite /or pennine/, phengite /a series name/, phlogopite, polylithionite, pyrophyllite, ripidolite, roscoelite, saponite, sauconite, sepiolite, serpentine, siderophyllite, stevensite, tainiolite, thuringite, vermiculite /trioctahedral and dioctahedral, distinguished in the 20th century/, volkonskoite, zinnwaldite /a series name/.