See R. Pantini, S. Gimignano e Certaldo (Bergamo, 1904), p. 101 seq.
| Fig. 1. |
| Fig. 2. |
CERUSSITE, a mineral consisting of lead carbonate (PbCO3), and an important ore of lead. The name (sometimes erroneously spelt cerusite) is from the Lat. cerussa, “white lead.” “Cerussa nativa” was mentioned by K. Gesner in 1565, and in 1832 F.S. Beudant applied the name céruse to the mineral, whilst the present form, cerussite, is due to W. Haidinger (1845). Popular names in early use were lead-spar and white-lead-ore.
Cerussite crystallizes in the orthorhombic system and is isomorphous with aragonite. Like aragonite it is very frequently twinned, the compound crystals being pseudo-hexagonal in form. Three crystals are usually twinned together on two faces of the prism m{110}, producing six-rayed stellate groups (figs, 1 and 2) with the individual crystals intercrossing at angles of nearly 60°. Twinning on the faces of the prism r{130}, the angles of which are also nearly 60°, produces a similar kind of grouping, but is much less common. Crystals are of frequent occurrence, and they usually have very bright and smooth faces. The mineral also occurs in compact granular masses, and sometimes in fibrous forms. It is usually colourless or white, sometimes grey or greenish in tint; it varies from transparent to translucent, and has an adamantine lustre. It is very brittle, and has a conchoidal fracture. Hardness 3-3½; sp. gr. 6.5. A variety containing 7% of zinc carbonate, replacing lead carbonate, is known as iglesiasite, from Iglesias in Sardinia, where it is found.
The mineral may be readily recognized by its characteristic twinning, in conjunction with the adamantine lustre and high specific gravity. It dissolves with effervescence in dilute nitric acid. Before the blow-pipe it fuses very readily, and gives reactions for lead. Cerussite occurs in metalliferous veins in association with galena, and has been formed by the action of carbonated waters on the galena; it is therefore found in the upper parts of the lodes together with other secondary minerals, such as limonite. Finely crystallized specimens have been obtained from the Friedrichssegen mine near Ems in Nassau, Johanngeorgenstadt in Saxony, Mies in Bohemia, Phenixville in Pennsylvania, Broken Hill in New South Wales, and several other localities. Delicate acicular crystals of considerable length were found long ago in the Pentire Glaze mine near St Minver in Cornwall. It is often found in considerable quantities, and contains as much as 77½% of lead.
(L. J. S.)
CERUTTI, GIUSEPPE ANTONIO GIACHIMO (1738-1792), French author and politician, was born at Turin on the 13th of June 1738. He joined the Society of Jesus and became professor at the Jesuit college at Lyons. In 1762, in reply to the attacks on his order, he published an Apologie générale de l’institut et de la doctrine des Jésuites, which won him much fame and some exalted patronage; notably that of the ex-king Stanislaus of Poland and of his grandson the dauphin. During the agitations that preceded the Revolution Cerutti took the popular side, and in 1788 published a pamphlet, Mémoire pour le peuple français, in which in a clear and trenchant style he advocated the claims of the tiers état. In May 1789 he presided over the electors of Paris, by whom in January 1791 he was chosen member of the administration of the department and afterwards deputy to the Legislative Assembly. He was a friend of Mirabeau, whose policy he supported and whose funeral oration he pronounced. He himself died on the 3rd of February 1792. Of Cerutti’s literary enterprises the most interesting, and probably the most influential, was the popular newspaper founded by him, on the 30th of September 1790, in collaboration with Rabaut Saint-Étienne and Philippe Antoine Grouvelle. Its character and objects are explained by its title: La Feuille villageoise, adressée chaque semaine à tous les villages de France pour les instruire des lois, des événements, des découvertes qui interessent tout ban citoyen, &c. It was continued by Grouvelle after Cerutti’s death, the last number appearing on the 2nd of August 1795.
Cerutti’s works were published in 1793 in 3 volumes. On the Mémoire pour le peuple français, see F.A. Aulard in La Révolution française, tom. xv. (1888).