Glauconite composition

Figure 3 lUite-glauconite compositions as a function of alumina and total iron oxides. Diamonds = illite, hollow squares = glauconite. Data for illite from Weaver and Pollard (1973), Newman and Brown (1978), and Baker (1997). Data for glauconite as in Figure 2. 

Celadonite [71606-04-7] is an iron-rich dioctahedral micaceous mineral that is similar to glauconite. Celadonite has a composition of (Na,K)Q... 

Other resolubilized trace metals precipitate as replacement ions in existing solids such as fecal pellets and bone. Examples of these fiassilized materials include barite, phosphorite, and glauconite. These precipitates contain small amounts of a variety of trace metals as well as other elements. As a result, their chemical composition is variable and their structure is usually amorphous, making it difficult to assign them an empirical formifia. 

Table 5.53 lists the general classification of micas with their main compositional terms. Stoichiometry obeys the general formula XF2 3Z40io(OH,F)2, where X = interlayer cations, Y = octahedrally coordinated cations of the 2 1 mixed layer, and Z = tetrahedrally coordinated cations of the 2 1 mixed layer. It must be noted that several compositional terms are indeed solid mixtures of more elementary components. In particular, glauconite has a complex chemistry and an Al Si diadochy of 0.33 3.67. (R and R terms in table 5.53 identify generic divalent and trivalent cations, respectively.)... 

The Rose Run Sandstone is the best characterized of the Cambrian sandstones because it is also an oil and gas reservoir (Fig. 3). It is also the only one of the Cambrian sandstones that is known to retain its sandstone composition in the eastern part of the state rather than passing laterally into carbonate. The Rose Run Sandstone is a sandy layer in the middle of the Knox Dolomite (Fig. 4), which across much of eastern Ohio lies at depths suitable for injection of supercritical C02 (Fig. 3). The Rose Run Sandstone was deposited in a passive margin phase of the Appalachian Basin and consists of interbedded layers of carbonate, primarily dolos-tone, and sandstone (Fig. 5). The sandstone is compositionally mature, consisting largely of quartz. Subordinate reactive minerals are the alkali feldspars and locally abundant glauconite (Fig. 5). Dolomite and quartz are the dominant cements (Janssens 1973 Riley et al. 1993). 

Figure 5. Typical X-ray diffraction traces of the (001) reflection for mica and mica-illite minerals. Assymmetry is shown towards large values. A - natural 2M muscovite B = natural illite (IMd) C - synthetic illite (lMd), 75% mica, 25% prophyllite composition D = synthetic 1M muscovite E - natural 1M glauconite F = synthetic 1M celadonite mica.

Figure 8. Compositions of natural potassic micas as a function of their AlVI—Fe + contents (octahedrally coordinated ions). Crosses represent phengite micas and dots celadonite-glauconite micas (K + Na + Ca/2 =...

The bulk compositions of natural illite, celadonite and glauconite ... 

Figure 13. Celadonite-glauconites as a function of their composition in the MR - 2r3 - 3r2 coordinates. It is important to remember that glauconites contain large quantities of Fe +. Crosses are celadonites and circles glauconites. Mo = montmorillonite Ce = celadonite mica Mi = muscovite.

However, it is evident that the celadonite-glauconites form a continuum between the tetrasilicic mica composition, illite and dioctahedral... 

Figure 14. Fe and A1 in octahedrally coordinated sites of illite, celadonite and glauconites. M-B = muscovite beidellite theoretical compositions Mo = montmorillonite (octahedral charge) Ce = celadonite open circles = illite triangles = glauconites dots = celadonites.

The approach used is to compare the composition of mixed layered mineral series—the illite-montmorillonite and the glauconite-montmorillonites. 

Different possible paths of glauconitization are Indicated in Figure 17. These paths indicate the variation in bulk composition of the pellet, as a function of K-Fe-Al variables. Depending upon the mineral (and chemical) composition of the starting material, different assemblages will be found in the pellets. 

It is possible that the mechanism of berthierine formation in this example is one of accretion, i.e., the grain would accumulate material at the exterior and this is eventually transformed into a chlorite composition. None of the grains was noted to have the form of a shell test as is often noted glauconite pellets. However the meta-berthierine pellets reported by Velde, et al.. (1974), were often found inside foraminifera tests. 

Those chlorites associated with mixed layered clay minerals are most silica-rich and have the greatest compositional variations for grains in a single thin section they tend to be iron-rich and aluminous. One chlorite vein was found to transect a glauconite pellet. This chlorite was quite iron-poor indicating attainment of a local chemical equilibrium between chlorite and iron mica upon its crystallization. 

Most commonly, zeolites are found in series of sedimentary rocks which contain pyroclastic material and are formed during the devitrification of this material. If the rocks are silica-rich, the zeolite species formed seems dependent upon the bulk composition and burial depth or temperature of formation (Hay, 1966). They are most frequently accompanied by silica in an amorphous or cryptocrystalline form (opal, chalcedony). Analcite and all other compositional intermediates up to the silica-rich clinoptilolite are found in this association. The most comifton clay mineral in such tuffs is montmorillonite. Zeolites are sometimes found with glauconite (Brown, et al . 1969) or celadonite (Hay, 1966 Iijima, 1970 Read and Eisenbacher, 1974) in pelitic layers or acidic eruptive rocks... 

The marine formations of late Cretaceous-Paleogene age on the southern part of the Russian Platform can be traced along strike for more than 2500 km and across it for more than 1000 m. They consist mostly of siliceous rocks (gaizes), clays, marls, chalk, and a small amount of sandstones and siltstones of quartzose composition. The rocks abound in glauconite and often contain phosphorites the clays are of a montmoril-lonitic composition, and a few pure bentonites have been found. Clinoptilolite occurs in almost all types of rocks of these formations. It fills pores and chambers of foraminifera and radiolaria and varies from fractions of a percent to 2-3% of the rock. It commonly makes up 70-80% of the 0.01- to 0.001-mm fraction. 

C eladonitc is an iron-rich dioctahedral micaceous mineral that is similar lo glauconite. Celadonite has a composition of (Na, Kla.s.tlFc. Alj M6i)(,vFc o.2o)r.ns(Si.i siAln,io)Oui(OH)i (39) and. like glauconile. has well crystalline, poorly crystalline, and inlerslratilied varieties. 

Glauconite is also a mica mineral with a large part of the octahedral A1 replaced by Fe(III). An average composition (14) is... 

Figure 2. Projection on planes Na—K—Mg and Ca—K—Mg of the composition of possible equilibrium phases and of marine sediment minus carbonate. CH = chlorite, IL — illite (hydromica), = montmorillonite, PH = phillipsite, SED = sediments [according to Goldschmidt (7)], CA = average calcareous, SI = average siliceous, AR = average argillaceous sediments (from Ref. 22), OW = ocean water, GL = glauconite,...

Dioctahedral micas (alkali interlayer ions having total charge near +1 per formula weight) which have either lMd or 1M polymorphs are either metastable muscovite forms or are micas with a composition differing from muscovite, e.g., glauconite, celadonite, and illite. ... 

A number of people have compiled data on the range and average composition of glauconite (Hendricks and Ross, 1941 Smulikowski, 1954 Borchert and Braun,1963). For the present review 69 analyses and 82 structural formulas from the literature were selected. 

Statistical data on composition of sixty-nine glauconites... 

In glauconites, octahedral A1 ranges from 0.00 to 1.28 and Fe3+ from 0.35 to 1.77 (11 out of 82 samples have more octahedral A1 than Fe3+). Within these limits, there is a continuous isomorphous series between A1 and Fe3+. The composition of the basic unit cell of many glauconites is within the range of composition of the nontronite clays however, on the average, glauconites have more Fe2 + and Mg and less tetrahedral A1 than the average nontronite. The most variable components within the layer are the Al3+ and Fe3+ ions in the octahedral sheet. Fe3+ increases as A1 decreases. 

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