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See also:TRACHYTE (Gr. rpaxus, rough) , in See also:petrology, a See also:group of volcanic rocks which consist mainly of sanidine (or glassy See also:orthoclase) See also:felspar. Very often they have See also:minute irregular See also:steam cavities which make the broken surfaces of specimens of these rocks rough and irregular, and from this See also:character they have derived their name. It was first given by }fatly to certain rocks of this class from See also:Auvergne, and was See also:long used in a much wider sense than that defined above, in fact it included See also:quartz-trachytes (now known as liparites and rhyolites) and See also:oligoclase-trachytes, which are now more properly assigned to andesites. The trachytes are often described as being the volcanic equivalents of the plutonic syenites. Their dominant See also:mineral, sanidine felspar, very commonly occurs in two generations, i.e. both as large well-shaped porphyritic crystals and in smaller imperfect rods or laths forming a finely crystalline groundmass. With this there is practically always a smaller amount of See also:plagioclase, usually oligoclase; but the potash felspar (sanidine) often contains a considerable See also:pro-portion of the soda felspar, and has rather the characteristics of anorthoclase or cryptoperthite than of pure sanidine.
Quartz is typically absent from the trachytes, but See also:tridymite (which likewise consists of See also:silica) is by no means uncommon in them. It is rarely in crystals large enough to be visible without the aid of the See also:microscope, but in thin slides it may appear as small hexagonal plates, which overlap and See also:form dense aggregates, like a See also:mosaic or like the tiles on a roof. They often See also:cover the surfaces of the larger felspars or See also:line the steam cavities of the See also:rock, where they may be mingled with amorphous See also:opal or fibrous See also:chalcedony. In the older trachytes secondary quartz is not rare, and probably sometimes results from the recrystallization of tridymite.
Of the ferromagnesian minerals See also:present See also:augite is the most See also:common. It is usually of See also:pale See also:green See also:colour, and its small crystals are often very perfect in form. 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:hornblende and See also:biotite occur also, and are usually surrounded by See also:black corrosion See also:borders composed of See also:magnetite and See also:pyroxene. Some-times the replacement is See also:complete and no hornblende or biotite is See also:left, though the outlines of the cluster of magnetite and augite may clearly indicate from which of these minerals it was derived. See also:Olivine is unusual, though found in some trachytes, like those of the Arso in See also:Ischia. Basic varieties of plagioclase, such as See also:labradorite, are known also as phenocrysts
in some See also:Italian trachytes. Dark brown varieties of augite and rhombic pyroxene (See also:hypersthene or See also:bronzite) have been observed but are not common. See also:Apatite, See also:zircon and magnetite are practically always present as unimportant See also:accessory minerals.
The trachytes being very See also:rich in potash felspar, necessarily contain considerable amounts of alkalis; in this character they approach the phonolites. Occasionally minerals of the felspathoid group, such as See also:nepheline, See also:sodalite and See also:leucite, occur, and rocks of this See also:kind are known as phonolitic trachytes. The soda-bearing amphiboles and pyroxenes so characteristic of the phonolites may also be found in some trachytes; thus aegirine or aegironic augite forms outgrowths on See also:diopside crystals, and riebeckite may be present in spongy growths among the felspars of the groundmass (as in the trachyte of Berkum on the See also:Rhine). Trachytic rocks are typically porphyritic, and some of the best-known examples, such as the trachyte of Drachenfels on the Rhine, show this character excellently, having large sanidine crystals of See also:tabular form an See also:inch or two in length scattered through their See also:fine-grained groundmass. In many trachytes, however, the phenocrysts are few and small, and the ground-See also:mass comparatively coarse. The ferromagnesian minerals rarely occur in large crystals, and are usually not conspicuous in See also:hand specimens of these rocks. Two types of ground-mass are generally recognized: the trachytic, composed mainly of long, narrow, sub-parallel rods of sanidine, and the orthophyric, consisting of small, squarish or rectangular prisms of the same mineral. Sometimes granular augite or spongy riebeckite occurs in the groundmass, but as a See also:rule this See also:part of the rock is highly felspathic. Glassy forms of trachyte (obsidians) occur, as in See also:Iceland, and pumiceous varieties are known (in See also:Teneriffe and elsewhere), but these rocks as contrasted with the rhyolites have a remark-ably strong tendency to crystallize, and are rarely to any considerable extent vitreous.
Trachytes are well represented among the See also:Tertiary and See also:Recent volcanic rocks of See also:Europe. In See also:Britain they occur in See also:Skye as See also:lava flows and as dikes or intrusions, but they are much more common on the See also:continent of Europe, as in the Rhine See also:district and the See also:Eifel, also in Auvergne, Bohemia and the Euganean Hills. In the neighbourhood of See also:Rome, See also:Naples and the See also:island of Ischia trachytic lavas and tuffs are of common occurrence. In See also:America trachytes are less frequent, being known in S. Dakota (Black Hills). In Iceland, the See also:Azores, Teneriffe and See also:Ascension there are Recent trachytic lavas, and rocks of this kind occur also in New See also:South See also:Wales (Cambewarra range), See also:East See also:Africa, See also:Madagascar, See also:Aden and in many other districts.
Among the older volcanic rocks trachytes also are not scarce, though they have often been described under the names orthophyre and orthoclase-See also:porphyry, while "trachyte " was reserved for Tertiary and Recent rocks of similar See also:composition. In See also:England there are See also:Permian trachytes in the See also:Exeter district, and Carboniferous trachytes are found in many parts of the central valley of See also:Scotland. The latter differ in no essential respect from their See also:modern representatives in See also:Italy and the Rhine valley, but their augite and biotite are often replaced by See also:chlorite and other secondary products.
Permian trachytes occur also in Thuringia and the See also:Saar district in See also:Germany.
Closely allied to the trachytes are the Keratophyres, which occur mainly in Palaeozoic strata in the Harz (Germany), in the See also:Southern Uplands of Scotland, in See also:Cornwall, &c. They are usually porphyritic and fluidal; and consist mainly of See also:alkali felspar (anorthoclase principally, but also See also:albite and orthoclase), with a small quantity of chlorite and See also:iron oxides. Many of them are lavas, butfor a lengthy monograph on a subject, dealing with it technically and authoritatively, whereas a See also:tract is understood to be brief and rather argumentative than educational. There is, again, the rarer word tractate, which is not a tract, in the precise sense, so much as a See also:short See also:treatise.
The word " tract " has come to be used for brief discourses of a moral and religious character only, and in modern practice it seems to be mainly confined to serious and hortatory themes. An See also:essay on See also:poetry, or the description of a passage of scenery, would not be styled a tract. In the See also:Protestant See also:world, the tract which See also:Luther composed in 1520, on the Babylonish captivity, has been taken more or less as the type of this See also:species of literature, which, however, existed long before his See also:day, both in Latin and in the See also:vernacular See also:tongues of western Europe. It is difficult, if not impossible, in See also:early See also:history, to distinguish the tract from other cognate forms of moralizing literature, but it may perhaps be said that the homilies of A3lfric (955-1025?) are the earliest specimens of this class in See also:English literature. Four centuries later Wyclif issued a See also:series of tracts, which were remarkable for their vigour, and exercised a strong See also:influence on See also:medieval See also:theology. See also:Bishop Reginald See also:Pecock published many controversial tracts between 1440 and 1460. See also:Sir See also:- THOMAS
- THOMAS (c. 1654-1720)
- THOMAS (d. 110o)
- THOMAS, ARTHUR GORING (1850-1892)
- THOMAS, CHARLES LOUIS AMBROISE (1811-1896)
- THOMAS, GEORGE (c. 1756-1802)
- THOMAS, GEORGE HENRY (1816-187o)
- THOMAS, ISAIAH (1749-1831)
- THOMAS, PIERRE (1634-1698)
- THOMAS, SIDNEY GILCHRIST (1850-1885)
- THOMAS, ST
- THOMAS, THEODORE (1835-1905)
- THOMAS, WILLIAM (d. 1554)
Thomas More, See also:John See also:Fisher (d. 1535) and See also:- WILLIAM
- WILLIAM (1143-1214)
- WILLIAM (1227-1256)
- WILLIAM (1J33-1584)
- WILLIAM (A.S. Wilhelm, O. Norse Vilhidlmr; O. H. Ger. Willahelm, Willahalm, M. H. Ger. Willehelm, Willehalm, Mod.Ger. Wilhelm; Du. Willem; O. Fr. Villalme, Mod. Fr. Guillaume; from " will," Goth. vilja, and " helm," Goth. hilms, Old Norse hidlmr, meaning
- WILLIAM (c. 1130-C. 1190)
- WILLIAM, 13TH
William See also:Tyndale were prominent writers of controversial See also:treatises. It was the See also:- MARTIN (Martinus)
- MARTIN, BON LOUIS HENRI (1810-1883)
- MARTIN, CLAUD (1735-1800)
- MARTIN, FRANCOIS XAVIER (1762-1846)
- MARTIN, HOMER DODGE (1836-1897)
- MARTIN, JOHN (1789-1854)
- MARTIN, LUTHER (1748-1826)
- MARTIN, SIR THEODORE (1816-1909)
- MARTIN, SIR WILLIAM FANSHAWE (1801–1895)
- MARTIN, ST (c. 316-400)
- MARTIN, WILLIAM (1767-1810)
Martin Marprelate agitation, in the reign of See also:Elizabeth, which led from 1588 to 1591 to the most copious See also:production of tracts in English literature; of these nearly See also:thirty survive. On the Puritan See also:side the See also:principal writers were John Udall (1560-1592), See also:- HENRY
- HENRY (1129-1195)
- HENRY (c. 1108-1139)
- HENRY (c. 1174–1216)
- HENRY (Fr. Henri; Span. Enrique; Ger. Heinrich; Mid. H. Ger. Heinrich and Heimrich; O.H.G. Haimi- or Heimirih, i.e. " prince, or chief of the house," from O.H.G. heim, the Eng. home, and rih, Goth. reiks; compare Lat. rex " king "—" rich," therefore " mig
- HENRY, EDWARD LAMSON (1841– )
- HENRY, JAMES (1798-1876)
- HENRY, JOSEPH (1797-1878)
- HENRY, MATTHEW (1662-1714)
- HENRY, PATRICK (1736–1799)
- HENRY, PRINCE OF BATTENBERG (1858-1896)
- HENRY, ROBERT (1718-1790)
- HENRY, VICTOR (1850– )
- HENRY, WILLIAM (1795-1836)
Henry See also:Barrowe (d. 1593), John See also:Penry (1559-1593) and See also:Job See also:Throckmorton (1545-1601), the tracts being printed in the See also:house of the last-mentioned; on the side of the Established See also:- CHURCH
- CHURCH (according to most authorities derived from the Gr. Kvpcaxov [&wµa], " the Lord's [house]," and common to many Teutonic, Slavonic and other languages under various forms—Scottish kirk, Ger. Kirche, Swed. kirka, Dan. kirke, Russ. tserkov, Buig. cerk
- CHURCH, FREDERICK EDWIN (1826-1900)
- CHURCH, GEORGE EARL (1835–1910)
- CHURCH, RICHARD WILLIAM (1815–189o)
- CHURCH, SIR RICHARD (1784–1873)
Church the principal authors were Bishop Thomas See also:- COOPER
- COOPER (or COUPER), THOMAS (c. 1517-1594)
- COOPER, ABRAHAM (1787—1868)
- COOPER, ALEXANDER (d. i66o)
- COOPER, CHARLES HENRY (18o8-1866)
- COOPER, JAMES FENIMORE (1789-1851)
- COOPER, PETER (1791-1883)
- COOPER, SAMUEL (1609-1672)
- COOPER, SIR ASTLEY PASTON (1768-1841)
- COOPER, THOMAS (1759–1840)
- COOPER, THOMAS (1805–1892)
- COOPER, THOMAS SIDNEY (1803–1902)
Cooper (1517-1594) and the poets See also:Lyly and See also:Nash. An enormous collection of tracts was published between 1717 and 1720 in elucidation of what is known as the Bangorian Controversy, set in See also:motion by a See also:sermon of See also:Benjamin See also:Hoadly, bishop of See also:Bangor, on " The Nature of the See also:Kingdom of See also:Christ " (1717). See also:Convocation considered this a treatise likely to impugn and impeach the royal supremacy in religious questions. A vast number of writers took part in the dispute, and Thomas See also:Sherlock (1678-1761) See also:fell into disgrace through the violence of his contributions to it. Convocation was finally obliged to give way.
The most famous collection of tracts published in the course of the 19th See also:century was that produced from 1833 onwards by See also:Newman, See also:Keble and E. B. See also:Pusey, under the See also:title of " Tracts for the Times." Among these Pusey's " Tract on See also:Baptism" (1835) and his " On the See also:Holy See also:Eucharist" (1836) had a profound effect in leading directly to the See also:foundation of the High Church party, so much so that the epithet " Tractarian " was barbarously coined to designate those who wished to oppose the spread of See also:rationalism by a quickening of the Church of England. In 1841 Newman's " Tract No. XC." was condemned by the heads of houses in See also:- OXFORD
- OXFORD, EARLS OF
- OXFORD, EDWARD DE VERE, 17TH EARL
- OXFORD, JOHN DE VERE, 13TH EARL OF (1443-1513)
- OXFORD, PROVISIONS OF
- OXFORD, ROBERT DE VERE, 9TH EARL OF (1362-1392)
- OXFORD, ROBERT HARLEY, 1ST
Oxford, and led to the definite organization of the High Church forces. (X.)
Tract See also:Societies are agencies for the production and See also:distribution, or the distribution only, of See also:Christian literature, more especially in
SiO2 Al20, Fe202 FeO MgO CaO Na2O See also:K20 See also:H2O
Riebeckite trachyte, Hohenberg, Berkum, Rhenish See also:Prussia . . 66•o6 16.46 2.25 1.10 0.19 0.79 6.81 5.52 0.62
Keratophyre, See also:- HAMILTON
- HAMILTON (GRAND or ASHUANIPI)
- HAMILTON, ALEXANDER (1757-1804)
- HAMILTON, ANTHONY, or ANTOINE (1646-1720)
- HAMILTON, ELIZABETH (1758–1816)
- HAMILTON, EMMA, LADY (c. 1765-1815)
- HAMILTON, JAMES (1769-1831)
- HAMILTON, JAMES HAMILTON, 1ST DUKE OF (1606-1649)
- HAMILTON, JOHN (c. 1511–1571)
- HAMILTON, MARQUESSES AND DUKES OF
- HAMILTON, PATRICK (1504-1528)
- HAMILTON, ROBERT (1743-1829)
- HAMILTON, SIR WILLIAM
- HAMILTON, SIR WILLIAM (1730-1803)
- HAMILTON, SIR WILLIAM ROWAN (1805-1865)
- HAMILTON, THOMAS (1789-1842)
- HAMILTON, WILLIAM (1704-1754)
- HAMILTON, WILLIAM GERARD (1729-1796)
Hamilton See also:- HILL
- HILL (0. Eng. hyll; cf. Low Ger. hull, Mid. Dutch hul, allied to Lat. celsus, high, collis, hill, &c.)
- HILL, A
- HILL, AARON (1685-175o)
- HILL, AMBROSE POWELL
- HILL, DANIEL HARVEY (1821-1889)
- HILL, DAVID BENNETT (1843–1910)
- HILL, GEORGE BIRKBECK NORMAN (1835-1903)
- HILL, JAMES J
- HILL, JOHN (c. 1716-1775)
- HILL, MATTHEW DAVENPORT (1792-1872)
- HILL, OCTAVIA (1838– )
- HILL, ROWLAND (1744–1833)
- HILL, SIR ROWLAND (1795-1879)
Hill, See also:Peebles, Scotland 64.38 16.98 4.04 - 0'28 1.08 7.57 4.30 1.64
Trachyte (Orthophyre) Garleton Hill, See also:Haddington,Scotland. . 61.35 16.88 0.41 5.01 0.44 2.39 5.26 6.12 1.70
Trachyte, See also:Monte Nuovo, Phlegraean See also:Fields, near Naples, Italy . . . 60.33 18.74 2.84 1.29 0.38 1.15 7.15 7.30 0.56
Trachyte, Algersdorf, Bohemia 64.69 18.39 - 3.44 0.49 1.72 4.61 6.46 0.24
others are probably dikes or thin intrusions. As the analyses given above will show, they differ from trachytes mainly in being richer in soda. U. S.
End of Article: TRACHYTE (Gr. rpaxus, rough)
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