where he remained till 1870, earning his bread by various means, but being nearly forgotten in his native land, to which he remained tenderly attached. From 1845 till 1860 (when the magazine was merged in the Bibliothèque universelle) Olivier and his wife wrote in the Revue suisse the Paris letter, which had been started by Ste Beuve in 1843, when Olivier became the owner of the periodical. After the war of 1870 he settled down in Switzerland, spending his summers at his beloved Gryon, and died at Geneva on the 7th of January 1876. Besides some novels, a semi-poetical work on the Canton of Vaud (2 vols., 1837–1841), and a volume of historical essays entitled Études d'histoire nationale (1842), he published several volumes of poems, Deux Voix (1835), Chansons lointaines (1847) and its continuation Chansons du soir (1867), and Sentiers de montagne (Gryon, 1875). His younger brother, Urbain (1810–1888), was well known from 1856 onwards as the author of numerous popular tales of rural life in the Canton of Vaud, especially of the region near Nyon.
Life by Rambert (1877), republished in his Écrivains de la Suisse romande (1889), and also prefixed to his edition of Olivier's Œuvres choisies (Lausanne, 1879). (W. A. B. C.)
OLIVINE, a rock-forming mineral composed of magnesium and ferrous orthosilicate, the formula being (Mg, Fe)2SiO4. The name olivine, proposed by A. G. Werner in 1790, alludes to the olive-green colour commonly shown by the mineral. The transparent varieties, or "precious olivine" used in jewelry, are known as chrysolite (q.v.) and peridot (q.v.). The term olivine is often applied incorrectly by jewellers to various green stones.
Olivine crystallizes in the orthorhombic system, but distinctly developed crystals are comparatively rare, the mineral more often occurring as compact or granular masses or as grains and blebs embedded in the igneous rocks of which it forms a constituent part. There are indistinct cleavages parallel to the macropinacoid (M in the fig.) and the brachypinacoid. The hardness is 6¾; and the sp. gr. 3·27–3·37,
but reaching 3·57 in the highly ferruginous variety known as hyalosiderite. The amount of ferrous oxide varies from 5 (about 9% in the gem varieties to 30% in hyalosiderite. The depth of the green, or yellowish-brown colour, also varies with the amount of iron. The lustre is vitreous. The indices of refraction (1·66 and 1·70) and the double refraction are higher than in many other rock-forming minerals; and these characters, together with the indistinct cleavage, enable the mineral to be readily distinguished in thin rock-sections under the microscope. The mineral is decomposed by hot hydrochloric acid with separation of gelatinous silica. Olivine often contains small amounts of nickel and titanium dioxide; the latter replaces silica, and in the variety known as titan-olivine reaches 5%.
Olivine is a common constituent of many basic and ultra basic rocks, such as basalt, diabase, gabbro and peridotite: the dunite, of Dun Mountain near Nelson in New Zealand, is an almost pure olivine-rock. In basalts it is often present as small porphyritic crystals or as large granular aggregates. It also occurs as an accessory constituent of some granular dolomitic limestones and crystalline schists. With enstatite it forms the bulk of the material of meteoric stones; and in another type of meteorites large blebs of glassy olivine fill spaces in a cellular mass of metallic iron.
Olivine is especially liable to alteration into serpentine (hydrated magnesium silicate); the alteration proceeds from the outside of the crystals and grains or along irregular cracks in their interior, and gives rise to the separation of iron oxides and an irregular net-work of fibrous serpentine, which in rock-sections presents a very characteristic appearance. Large greenish-yellow crystals from Snarum in Buskerud, Norway, at one time thought to be crystals of serpentine, really consist of serpentine pseudomorphous after olivine. Many of the large rock-masses of serpentine have been derived by the serpentinization of olivine rocks. Olivine also sometimes alters, especially in crystalline schists, to a fibrous, colourless amphibole, to which the name pilite has been given. By ordinary weathering processes it alters to limonite and silica.
Closely related to olivine are several other species, which are included together in the olivine group: they have the orthosilicate formula R′′2SiO4, where R′′ represents calcium, magnesium, iron, manganese and rarely zinc; they all crystallize in the orthorhombic system, and are isomorphous with olivine. The following may be mentioned:—
Monticellite, CaMgSiO4, a rare mineral occurring as yellowish-grey crystals and grains in granular limestone at Monte Somma, Vesuvius.
Forsterite, Mg2SiO4, as colourless or yellowish grains embedded in many crystalline limestones.
Fayalite, Fe2SiO4, or iron olivine is dark brown or black in colour. It occurs as nodules in a volcanic rock at Fayal in the Azores, and in granite at the Mourne Mountains in Ireland; and as small crystals in cavities in rhyolite at the Yellowstone Park, U.S.A. It is a common constituent of crystalline iron slags.
Tephroite, Mn2SiO4, a grey (τεφρός, ash-coloured), cleanable mineral occurring with other manganiferous minerals in Sweden and New Jersey. (L. J. S.)
OLLIVIER, OLIVIER ÉMILE (1825–), French statesman, was born at Marseilles on the 2nd of July 1825. His father, Demosthènes Ollivier (1799–1884), was a vehement opponent of the July monarchy, and was returned by Marseilles to the Constituent Assembly in 1848. His opposition to Louis Napoleon led to his banishment after the coup d'état of December 1851, and he only returned to France in 1860. On the establishment of the short-lived Second Republic his father's influence with Ledru-Rollin secured for Émile Ollivier the position of commissary-general of the department of Bouches-du-Rhône. Ollivier was then twenty-three and had just been called to the Parisian bar. Less radical in his political opinions than his father, his repression of a socialist outbreak at Marseilles commended him to General Cavaignac, who continued him in his functions by making him prefect of the department. He was shortly afterwards removed to the comparatively unimportant prefecture of Chaumont (Haute-Marne), a semi-disgrace which he ascribed to his father's enemies. He therefore resigned from the civil service to take up practice at the bar, where his brilliant abilities assured his success.
He re-entered political life in 1857 as deputy for the 3rd circumscription of the Seine. His candidature had been supported by the Siècle, and he joined the constitutional opposition. With Alfred Darimon, Jules Favre, J. L. Hénon and Ernest Picard he formed the group known as Les Cinq, which wrung from Napoleon III. some concessions in the direction of constitutional government. The imperial decree of the 24th of November, permitting the insertion of parliamentary reports in the Moniteur, and an address from the Corps Législatif in reply to the speech from the throne, were welcomed by him as a first instalment of reform. This acquiescence marked a considerable change of attitude, for only a year previously a violent attack on the imperial government, in the course of a defence of Étienne Vacherot, brought to trial for the publication of La Démocratie, had resulted in his suspension from the bar for three months. He gradually separated from his old associates, who grouped themselves around Jules Favre, and during the session of 1856–1867 Ollivier formed a third party, which definitely supported the principle of a Liberal Empire. On the last day of December 1866, Count A. F. J. Walewski, acting in continuance of negotiations already begun by the duc de Morny, offered Ollivier the ministry of education with the function of representing the general policy of the government in the Chamber. The imperial decree of the 19th of January 1867, together with the promise inserted in the Moniteur of a relaxation of the stringency of the press laws and of concessions in respect of the right of public meeting, failed to satisfy Ollivier's demands, and he refused office. On the eve of the general election of 1869 he published a manifesto, Le 19 Janvier, in justification of his policy. The sénatus-consulte of the 8th of September 1869 gave the two chambers the ordinary
