|
MARCASITE , a See also: mineral with the same chemical See also:composition as See also:pyrites, being See also:iron disulphide FeS2, but crystallizing in the orthorhombic instead of in the cubic See also:system. The name is of Arabic origin and was See also:long applied to crystallized pyrites (q.v.); it was restricted to the See also:present See also:species by W. See also:Haidinger in 1845. The mineral was known to G. See also:Agricola in 1546 under the names Wasserkies or Wesserkies and Leberkies, and it has been variously known as See also:- WHITE
- WHITE, ANDREW DICKSON (1832– )
- WHITE, GILBERT (1720–1793)
- WHITE, HENRY KIRKE (1785-1806)
- WHITE, HUGH LAWSON (1773-1840)
- WHITE, JOSEPH BLANCO (1775-1841)
- WHITE, RICHARD GRANT (1822-1885)
- WHITE, ROBERT (1645-1704)
- WHITE, SIR GEORGE STUART (1835– )
- WHITE, SIR THOMAS (1492-1567)
- WHITE, SIR WILLIAM ARTHUR (1824--1891)
- WHITE, SIR WILLIAM HENRY (1845– )
- WHITE, THOMAS (1628-1698)
- WHITE, THOMAS (c. 1550-1624)
white pyrites, hepatic pyrites, lamellar pyrites, radiated pyrites (See also:German Strahlkies) and prismatic pyrites. The orthorhombic See also:form of the crystals, as distinct from the cubic form of pyrites, was recognized by See also:Rome de l'Isle in 1772, though later R. J. See also:Hauy considered the crystals to be only distorted cubic forms.
The crystals are isomorphous with See also:mispickel (q.v.), but only rarely are they distinctly See also:developed and See also:simple (fig.). Usually. they are twinned on a See also:prism See also:plane, M, producing pentagonal stellate See also:groups of five crystals; twinning on the See also:plain g, in which the crystals intercross at angles of nearly 6o°, is less See also:common. This frequent twinning gives rise to characteristic forms, with many re-entrant angles, to which the names " See also:spear pyrites " and " cockscomb pyrites " are applied.
The commonest See also:state of See also:aggregation is that of radially arranged See also:fibres, the See also:external See also:surface of the See also:mass being globular, nodular or stalactitic in form.
Apart from crystalline form, the external characters of marcasite are very similar to those of pyrites, and when distinct crystals are not available the two species cannot always be easily distinguished. The See also: colour is usually See also:pale See also:bronze-yellow, often rather lighter than that of pyrites; on freshly fractured surfaces of pure marcasite the colour is See also:tin-white, but this rapidly tarnishes on exposure to See also:air. The lustre is metallic and brilliant. The streak is greyish or brownish-See also:black. The hardness (6–62) is the same as that of pyrites, and the specific gravity (4.8–4.9) as a See also:rule rather less. Arsenical varieties of marcasite, containing up to 5% of See also:arsenic, are known as lonchidite and kyrosite.
Marcasite readily oxidizes on exposure to moist air, with the See also:production of sulphuric See also:acid and a white fibrous efflorescence of ferrous sulphate, and in course of See also:- TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
- TIME, MEASUREMENT OF
- TIME, STANDARD
time specimens in collections often became completely disintegrated. In nature it is frequently altered to See also:limonite with the separation of native See also:sulphur. Marcasite is thus the less See also:stable of the two modifications of iron disulphide. Many experiments have been made with a view to determining the difference in chemical constitution of marcasite and pyrites, but with no very definite results. It is a noteworthy fact that whilst pyrites has been prepared artificially, marcasite has not.
Marcasite occurs under the same conditions as pyrites, but is much less common. Whilst pyrites is found abundantly in the older crystalline rocks and slates, marcasite is more abundant in See also: clays, and has often been formed as a See also:concretion around organic remains. It is abundant, for example, in the plastic See also:clay of the See also:- BROWN
- BROWN, CHARLES BROCKDEN (1771-181o)
- BROWN, FORD MADOX (1821-1893)
- BROWN, FRANCIS (1849- )
- BROWN, GEORGE (1818-188o)
- BROWN, HENRY KIRKE (1814-1886)
- BROWN, JACOB (1775–1828)
- BROWN, JOHN (1715–1766)
- BROWN, JOHN (1722-1787)
- BROWN, JOHN (1735–1788)
- BROWN, JOHN (1784–1858)
- BROWN, JOHN (1800-1859)
- BROWN, JOHN (1810—1882)
- BROWN, JOHN GEORGE (1831— )
- BROWN, ROBERT (1773-1858)
- BROWN, SAMUEL MORISON (1817—1856)
- BROWN, SIR GEORGE (1790-1865)
- BROWN, SIR JOHN (1816-1896)
- BROWN, SIR WILLIAM, BART
- BROWN, THOMAS (1663-1704)
- BROWN, THOMAS (1778-1820)
- BROWN, THOMAS EDWARD (1830-1897)
- BROWN, WILLIAM LAURENCE (1755–1830)
Brown See also:Coal formation at Littmitz, near See also:Carlsbad, in Bohemia, at which See also:place it has been extensively See also:mined for the manufacture of sulphur and ferrous sulphate. In the See also:Chalk of the See also:south-See also:east of See also:England nodules of marcasite with a fibrous radiated structure are abundant, and in the Chalk See also:Marl between See also:Dover and See also:Folkestone See also:fine twinned groups of " spear pyrites " are common. The mineral is also met with in metalliferous See also:veins, though much less frequently than pyrites; for example the " cockscomb pyrites " of the See also:lead
mines of See also:Derbyshire and See also:Cumberland. (L. J. S.)
MARCEAU-DESGRAVIERS, See also:FRANCOIS SEVERIN (176)–1796), See also:French See also:general, was See also:born at See also:Chartres on the 1st of See also:March 1769. His See also:father was a See also:law officer, and he was educated for a legal career, but at the See also:age of sixteen he enlisted in the See also:regiment of See also:Savoy-Carignan. Whilst on furlough in See also:Paris Marceau joined in the attack on the See also:Bastille (See also:July 14, 1789); after that event he took his See also:discharge from the See also:regular See also:army and returned to Chartres, but the embarrassments of his See also:family soon compelled him to seek fresh military enployment. He became See also:drill instructor, and afterwards See also:captain in the depart-See also:mental (See also:Eure-et-See also:Loire) regiment of the See also:National Guard. See also:Early
in March 1792 he was elected See also:lieutenant-See also:colonel of one of the battalions of the Eure-et-Loire; he took See also:part in the See also:defence of See also:Verdun in 1792, and it See also:fell to his See also:lot to See also:bear the proposals of See also:capitulation to the Prussian See also:camp. The spiritless conduct of the defenders excited the wrath of the revolutionary authorities, and Marceau was fortunate in escaping See also:arrest and finding re-employment as a captain in the regular service.
Early in 1793 he became with other See also: officers " suspect, " and was for some time imprisoned. On his See also:release he hurried to take part in the defence of See also:Saumur against the Vendean royalists, and distinguished himself at the combat of Saumur (See also:June to, 1793) by gallantly rescuing the representative Bourbotte from the hands of the insurgents. The See also:Convention voted him the thanks of the See also:country, and thenceforward his rise was rapid. His conduct at Chantonnay (See also:Sept. 5) won him the provisional See also:rank of general of See also:brigade. On the 17th of See also:October he See also:bore a See also:great part in the victory of See also:Cholet, and on the See also:- FIELD (a word common to many West German languages, cf. Ger. Feld, Dutch veld, possibly cognate with O.E. f olde, the earth, and ultimately with root of the Gr. irAaror, broad)
- FIELD, CYRUS WEST (1819-1892)
- FIELD, DAVID DUDLEY (18o5-1894)
- FIELD, EUGENE (1850-1895)
- FIELD, FREDERICK (18o1—1885)
- FIELD, HENRY MARTYN (1822-1907)
- FIELD, JOHN (1782—1837)
- FIELD, MARSHALL (183 1906)
- FIELD, NATHAN (1587—1633)
- FIELD, STEPHEN JOHNSON (1816-1899)
- FIELD, WILLIAM VENTRIS FIELD, BARON (1813-1907)
field of this See also:battle began his friendship with Kleber. For the victory of Cholet Kleber was made general of See also:division and Marceau confirmed as general of brigade. Their See also:advice was of the greatest value to the generals in command, and the military talents of each were the See also:complement of the other's. Marceau, who became general of division (Nov. 1o), succeeded to the See also:chief command ad See also:interim, and with his friend won important victories near Le Mans (Dec. 12–13) and Savenay (Dec. 23). After the battle of Le Mans, Marceau rescued and protected a See also: young Royalist See also:lady, Angelique See also:des Mesliers. It is often supposed that he was in love with his prisoner; but the help even of the See also:commander-in-chief did not avail to See also:save her from the See also:guillotine (See also:Jan. 22, 1794). Marceau had already retired from the See also:war, exhausted by the fatigues of the See also:campaign, and he and Kleber were saved from arrest and See also:execution only by the intervention of Bourbotte. Marceau became affianced about this time to Agathe Lepretre de Chateaugiron, but his See also:constant military employment, his broken See also:health, and the opposition of the See also:comte de ChMeaugiron on the one See also:hand and of Marceau's devoted See also:half-See also:sister " Emira," wife of the Republican politician Sergent, on the other, prevented the realization of his hopes. After spending the See also:winter of 1793–1794 in Paris he took a command in the army under See also:Jourdan, in which Kleber also served. He took part in the various battles about See also:Charleroi, and at the final victory of See also:Fleurus (June 26, 1794) he had a See also:horse shot under him. He distinguished himself again at Jiilich and at Aldenhoven, and stormed the lines of See also:Coblenz on the 23rd of October. With the Army of the Sambre and See also:Meuse he took his See also:share in the campaign of 1795 on the See also:Rhine and the See also:Lahn, distinguishing himself particularly with Kleber in the fighting about Neuwied on the 18th and 19th of October, and at Sulzbach on the 17th of See also:December. In the campaign of 1796 the famous invasion of See also:Germany by the armies of Jourdan and See also:Moreau ended in disaster, and Marceau's men covered Jourdan's See also:retreat over the Rhine. He fought the desperate actions on the Lahn (Sept. 16 and 18), and at Altenkirchen on the 19th received a mortal See also:wound, of which he died on the 21st, at the early age of twenty-seven. The Austrians vied with his own countrymen in doing See also: honour to the dead general. His See also:body was burned, and- his ashes, which at the time were placed under a See also:pyramid designed by Kleber, were transferred in 1889 to the See also:Pantheon at Paris.
See See also:Maze, Le General Marceau (1889) ; Parfait, Le General Marceau (1892) ; and T. C. See also:- JOHNSON, ANDREW
- JOHNSON, ANDREW (1808–1875)
- JOHNSON, BENJAMIN (c. 1665-1742)
- JOHNSON, EASTMAN (1824–1906)
- JOHNSON, REVERDY (1796–1876)
- JOHNSON, RICHARD (1573–1659 ?)
- JOHNSON, RICHARD MENTOR (1781–1850)
- JOHNSON, SAMUEL (1709-1784)
- JOHNSON, SIR THOMAS (1664-1729)
- JOHNSON, SIR WILLIAM (1715–1774)
- JOHNSON, THOMAS
Johnson, Marceau (See also:London, 1896).
End of Article: MARCASITE
Additional information and Comments
There are no comments yet for this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.
Links to articles and home page are always encouraged.
|
del.icio.us it!