[mod. ad. Gr. ἀλλότροπία variation, changeableness, f. ἀλλότροπος of other manner; f. ἄλλος other, different + τρόπος turn (of mind), manner, f. τρέπ-ειν to turn.] The variation of physical properties without change of substance to which certain elementary bodies are liable, first noticed by Berzelius in the case of charcoal and the diamond.
1850. Ansted, Elem. Geol., 151. Isomorphism, a converse phenomenon to that of allotropy.
1863. Watts, Chem. Dict., II. 423. Instances of inorganic isomerism are usually called instances of allotropy … Sulphur, phosphorus, carbon, and many other elements present … examples of allotropy.
