Allotropy (so named by J. J. Berzelius in 1841) refers to the existence of a chemical element in two or more distinct forms having different crystalline structures and/or physical properties. Allotropes may differ with respect to density, melting point, molar volume, color, and other physical properties. In some cases, there is a reversible, in others an irreversible transition from one allotrope to another.
Examples of Allotropy include:
carbon: chaoite , graphite , and lonsdaleite (hexagonal); diamond (isometric).
sulfur : native or α-sulfur (orthorhombic); γ-sulfur or rosickyite (monoclinic).
phosphorus: white/yellow (two forms: cubic and orthorhombic), violet and black (thus, four allotropes of contrasting properties); red phosphorus is a mixture.
tin : white (tetrahedral); gray (cubic).
iron: α-iron or kamacite (body-centered cubic and magnetic); γ-iron or taenite(face-centered cubic and nonmagnetic); δ-iron or ferrite (body-centered cubic and stable only...
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Reference
Weaver, E. C., 1966. Allotropes, in G. L. Clark, ed., Encyclopedia of Chemistry, 2nd ed. New York: Reinhold.
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© 1981 Hutchinson Ross Publishing Company
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Fairbridge, R.W. (1981). Allotropy . In: Mineralogy. Encyclopedia of Earth Science. Springer, Boston, MA. https://doi.org/10.1007/0-387-30720-6_3
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DOI: https://doi.org/10.1007/0-387-30720-6_3
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