Min. [Named 1852 from Barranco Jaroso, in Spain: see -ITE.] A hydrous sulphate of iron and potassium, occurring usually in yellowish rhombohedral crystals.
1854. Dana, Min. (ed. 4), 389. Jarosite … may be isomorphous with alunite.
1883. M. F. Heddle, in Encycl. Brit., XVI. 402/2. Jarosite … fibrous in nodules or incrusting.
