Clinochlore


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clinochlore

[′klī·nə‚klȯr]
(mineralogy)
(Mg,Fe,Al)3(Si,Al)2O5(OH)4 Green mineral of the chlorite group, occurring in monoclinic crystals, in folia or scales, or massive.

Clinochlore

 

a mineral of the chlorite group; one of the layered aluminosilicates.

The approximate chemical composition of chlinochlore is

(Mg, Fe)4.75 Al,1.25 [Al,1.25 Si2.75 O10] (OH)8

The ratios of magnesium to aluminum and aluminum to silicon vary considerably, although clinochlore is primarily a magnesium-aluminum chlorite. The low-iron variety of clinochlore is known as leichtenbergite (colorless). Clinochlore containing admixtures of chromium is called kotschubeite (pinkish-violet).

Clinochlore crystallizes in the monoclinic system, forming small pseudohexagonal plumose crystals with good cleavage. Most often, clinochlore forms microplumose aggregates. Its color ranges from dark gray-green to light olive-green. Clinochlore is transparent in the form of thin laminae. Its hardness on the mineralogical scale is 2–2.5; its density varies between 2,610 and 2,780 kg per cu m. It is a rock-forming mineral in chlorite shales and occurs in other metamorphic rocks as well (appearing as a result of changes in pyroxenes, amphiboles, garnets, ferromagnesian mica). Clinochlore also exists in contact-meta-somatic rocks, such as skarns, and in modified secondary rocks in hydrothermal lodes. Clinochlore is very widely distributed in nature.

G. P. BARSANOV

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References in periodicals archive ?
Welch, "The effect of pressure upon hydrogen bonding in chlorite: a raman spectroscopic study of clinochlore to 26.5 GPa," American Mineralogist, vol.
Castellanos and co-workers (personal communication) described in detail the characteristic mineral assemblages from reaction zones recognized in marbles, which include calcite + graphite [+ or -] quartz; calcite + diopside [+ or -] tremolite [+ or -] epidote-group minerals [+ or -] muscovite; calcite + wollastonite + quartz + garnet + diopside; calcite + dolomite + Ti-clinohumite + diopside + forsterite + clinochlore [+ or -] graphite; calcite + forsterite + tremolite; dolomite + calcite + clinochlore.
The allochthonous minerals (chamosite, glauconite, chlorite and nacrite / clinochlore) could be due to the influx of shallow marine water into the passive continental depositional basin.
Muestras SI53M2B SI53M2A Fases Montmorillonite [13-135] [13-135] Clinochlore [29-701] [29-701] Muscovite [7-42] [7-42] Amphibole [73-1135] Quartz [[86-1628] [86-1628] Albite [78-1995] [78-1995] Tabla 2: Parametros hiperfinos de los minerales identificados en la parte bruta y en la fraccion arcillosa.
* Q *, G * G **, KNA ** Cernuc Q *, Mi * Q *, F-Mi **, K **, Mi **, (central Bohemia, clinochlore in the rusty Velvary area) layer ** Py *** Table 2 A summary of results from mercury intrusion porosimetry.
amethysts from the Painter Farm, microclines from the Poorhouse quarry, clinochlore variety kammererite from the Scott mine, and others.
Thus, various equilibria (e.g., E1 and E2 given in Table 2) could be calculated for T values between 250[degrees]C and 400[degrees]C considering the above components, the clinochlore (= [Mg.sub.5]Al[Al[Si.sub.3[[O.sub.10]][(OH).sub.8]) component in chlorite, the muscovite (KAl2[AlSi3O10](OH)2) component in potassic white mica as well as K-feldspar, quartz and [H.sub.2]O.
Chrysotile (i.e., fibrous asbestos) is the most common mineral phase found in veins and shear zones crosscutting the serpentinite rocks (Figure 5), along with dolomite and trace amounts of clinochlore (i.e., sample R10).
The intensity curves and stick pattern for all the three major minerals, Quartz, Muscovite and Clinochlore is given in Figure 2 and 3 respectively.
Chlorite compositions are close to the ideal clinochlore composition ([Mg.sub.5][Al.sub.2][Si.sub.3][O.sub.10][(OH).sub.8]), with 3 ([+ or -] 0.1) Si, 2 (+ or -] 0.1) Al, and 5 ([+ or -]0.2) divalent ([R.sup.2+]) ions per unit formula (Appendix Table A3).
The commonest species in sediments are the Mg- and [Fe.sup.2+] -rich trioctahedral chlorites, namely clinochlore and chamosite, and the Al-rich dioctahedral species, donbassite.
Lawrence County, New York and clinochlore from West-townr Chester County, Pennsylvania.