MONAZITE, a mineral consisting of phosphate of the cerium metals, the formula being small and variable amounts of thorium I-1 o%) and yttrium are usually also present. It is of considerable commercial importance as a source of thoria for the manufacture of mantles for incandescent gas-lighting ; the cerium is used to a limited extent in pharmacy, and alloyed with iron it forms the "flints" (sparking metal) of automatic lighters.
Crystals of monazite belong to the monoclinic system, and are usually flattened parallel to the ortho-pinacoid. The large (up to 5in. in length) reddish-brown, dull and opaque crystals from Nor way and the Urals are simple in form, whilst the small, translucent, honey-yellow crystals from the Alps are bounded by numerous bright faces. The hardness is 54, and the specific gravity 5.1-5.2. Light which has traversed a crystal or grain of monazite exhibits a characteristic absorption spectrum, and this affords a ready means of detecting the mineral.
As minute crystals monazite is of wide distribution in granites and gneisses, being present in very small amounts as an accessory constituent of these rocks. By powdering the rock and washing away the lighter minerals in a stream of water the heavy minerals (zircon, anatase, rutile, magnetite, garnet, monazite, xenotime, etc.) may be collected. This separation has been effected naturally by the weathering and disintegration of the rocks and the ac cumulation of the heavier minerals in the beds of streams. Under these conditions monazite has been found as rounded water-worn grains in the alluvial gold-washings of the Urals, Finland, Siberia, the United States, Brazil, Colombia, New South Wales, etc. Larger crystals of monazite are found embedded in pegmatite veins in the Ilmen mountains (southern Urals) ; at Arendal and other places in southern Norway, where it is collected in the felspar quarries to the extent of about one ton per annum ; and in the mica mines at Villeneuve, Quebec, where masses of monazite weighing 2o1b. have been found.
The deposits worked commercially are the monazite-bearing sands of North Carolina, Brazil, Ceylon and Travancore. In Brazil it occurs in river-gravels and also in the sand on the sea beaches; an extensive accumulation of very rich monazite sand occurs on the seashore near Alcobaca in Bahia, and this has been shipped as ballast in the natural state. In Travancore the sands of the sea-shore and of the sand-dunes along the coast are con centrated by washing, and the grains of monazite are separated electromagnetically from the associated zircon and ilmenite.
See "Monazite," Imp. Mineral Resources Bureau (London, 192o). MONBODDO, JAMES BURNETT, LORD T. ( Scottish judge and anthropologist, born at Monboddo, Kincar dineshire, studied at Aberdeen and Edinburgh. He was made a lord of session in 1767 with the title of Lord Monboddo. In his Antient Metaphysics (1779-99), Monboddo conceived man as gradually elevating himself from an animal condition, in which his mind is immersed in matter, to a state in which mind acts independently of body. In his equally voluminous work, The Origin and Progress of Language (1773), he brought man under the same species as the orang-outang. He traced the gradual elevation of man to the social state, which he conceived as a natural process determined by "the necessities of human life." He looked on language (which is not "natural" to man in the sense of being necessary to his self-preservation) as a consequence of his social state. His views about the origin of society and language and the faculties by which man is distinguished from the brutes have many curious points of contact with Darwinism and neo-Kantianism. He died on May 26, 1799.
Boswell's Life of Johnson gives an account of Johnson's visit to Burnett at Monboddo, and is full of references to the natural con temporary view of a man who thought that the human race could be descended from monkeys.