The chlorite group of minerals derives its name from the common green color of most varieties, although specimens of many diverse colors are known to exist. The morphology ranges from fine-grained earthy masses to spherules and rosettes to scaly flakes and pseudohexagonal platelets. There is a perfect basal cleavage parallel to (001). The cleavage flakes are flexible but inelastic, with a luster varying from pearly or viterous to dull and earthy. The hardness on the cleavage is about 2 1/2. The specific gravity varies between 2.6 and 3.3 as a function of composition.
Chlorite is a common accessory mineral in low- to medium-grade regional metamorphic rocks, and may be the most abundant mineral in metamorphic rocks of the chlorite zone. It is an occasional constituent of igneous rocks, in most cases probably forming secondarily by deuteric or hydrothermal alteration of primary ferromagnesian minerals. Chloriteis found in pegmatites and fessure vein deposits. It is a common constituent...
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References
Bailey, S. W., and Brown, B. E., 1962. Chlorite polytypism: I. Regular and semi-random one-layer structures, Am. Mineralogist, 47, 819–850.
Bayliss, P., 1975. Nomenclature of the trioctahedral chlorites, Can. Mineralogist, 13, 178–180.
Foster, Margaret D., 1962. Interpretation of the composition and a classification of the chlorites, U.S. Geol. Surv. Prof. Paper 414-A, 33p.
Foster, Margaret D., 1964. Water content of micas and chlorites, U.S. Geol. Surv. Prof. Paper 474-F, 15p.
Pauling, L., 1930. The structure of the chlorites, Proc. Natl. Acad. Sci., 16, 578–582.
Cross-references
Clays, Clay Minerals; Diagenetic Minerals; Green River Mineralogy; Mica Group; Phyllosilicates; Pleochroic Halos; Topotaxy; also, see mineral glossary.
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Bailey, S.W. (1981). Chlorite group . In: Mineralogy. Encyclopedia of Earth Science. Springer, Boston, MA. https://doi.org/10.1007/0-387-30720-6_22
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