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 See also: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: