Tags: Chemical Substance, Mineral.
Ceylonite (first cited 1793) and pleonaste (first cited 1801) are dingy blue or grey to black varieties of spinel. Ceylonite named for the island of Ceylon is a ferroan spinel with Mg:Fe from 3:1 and 1:1 and little or no ferric iron. Pleonaste is named from the Greek for ‘abundant’ for its many crystal forms and is distinguished chemically by low Mg:Fe ratios of approximately 1:3.
