JARNAC, a town of western France in the department of Charente, on the right bank of the river Charente, and on the railway 23 m. W. of Angoulême, between that city and Cognac. Pop. (1906), 4493. The town is well built; and an avenue, planted with poplar trees, leads to a handsome suspension bridge. The church contains an interesting ogival crypt. There are communal colleges for both sexes. Brandy, wine and wine-casks are made in the town. Jarnac was in 1569 the scene of a battle in which the Catholics defeated the Protestants. A pyramid marks the spot where Louis, Prince de Condé, one of the Protestant generals, was slain. Jarnac gave its name to an old French family, of which the best known member is Gui Chabot, comte de Jarnac (d. c. 1575), whose lucky backstroke in his famous duel with Châteigneraie gave rise to the proverbial phrase _coup de jarnac_, signifying an unexpected blow. JARO, a town of the province of Iloílo, Panay, Philippine Islands, on the Jaro river, 2 m. N.W. of the town of Iloílo, the capital. Pop. (1903), 10,681. It lies on a plain in the midst of a rich agricultural district, has several fine residences, a cathedral, a curious three-tiered tower, a semi-weekly paper and a monthly periodical. Jaro was founded by the Spanish in 1584. From 1903 until February 1908 it was part of the town or municipality of Iloílo. JAROSITE, a rare mineral species consisting of hydrous potassium and aluminium sulphate, and belonging to the group of isomorphous rhombohedral minerals enumerated below:-- Alunite K2 [Al(OH)2]6 (SO4)4 Jarosite K2 [Fe(OH)2]6 (SO4)4 Natrojarosite Na2 [Fe(OH)2]6 (SO4)4 Plumbojarosite Pb [Fe(OH)2]8 (SO4)4 Jarosite usually occurs as drusy incrustations of minute indistinct crystals with a yellowish-brown colour and brilliant lustre. Hardness 3; sp. gr. 3.15. The best specimens, consisting of crystalline crusts on limonite, are from the Jaroso ravine in the Sierra Almagrera, province of Almeria, Spain, from which locality the mineral receives its name. It has been also found, often in association with iron ores, at a few other localities. A variety occurring as concretionary or mulberry-like forms is known as moronolite (from Gr. [Greek: môron], "mulberry," and [Greek: líthos], "stone"); it is found at Monroe in Orange county, New York. The recently discovered species natrojarosite and plumbojarosite occur as yellowish-brown glistening powders consisting wholly of minute crystals, and are from Nevada and New Mexico respectively. (L. J. S.)