See also:

• METASOMATISM (Gr. /sera, change, o-wµa, body)

METASOMATISM (Gr. /sera, See also:

• CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change, o-wµa, See also:

• BODY

body)  , in See also:

• PETROLOGY

petrology, a See also:

• PROCESS

process of alteration of rocks by which their chemical See also:

• COMPOSITION
• COMPOSITION (Lat. compositio, from componere, to put together)

composition is modified, new substances being introduced while those originally See also:

• PRESENT

present are partly or wholly removed in See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution . For example a See also:

• LIMESTONE

limestone may be converted into a siliceous chert, a See also:

• DOLOMITE

dolomite, an ironstone, or a See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass of metalliferous ores by metasomatic alteration . The process is usually incomplete, greater or smaller portions of the See also:

• ORIGINAL

original See also:

• ROCK
• ROCK (O.Fr. rake, Sp. rota, Ital. rocca; possibly from a Lat. form rupica, from rupes, rock)
• ROCK, DANIEL (1799–187t)

rock remaining . The agencies of See also:

• METASOMATISM (Gr. /sera, change, o-wµa, body)

metasomatism are in nearly all cases aqueous solutions; probably they were often at a high temperature, as metasomatic changes are especially liable to occur in the vicinity of igneous intrusions (laccolites, dikes and necks) where large quantities of See also:

• WATER

water were given off by the volcanic magma at a 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 when it had solidified but was not yet See also:

• COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold . Metasomatism also usually goes on at some See also:

• DEPTH

depth, so that we may readily believe that it is favoured by increase of pressure . On the other See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, there are many instances in which these processes cannot be shown to have taken See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place at temperatures or pressures above those which normally exist in the upper See also:

• PART

part of the See also:

• EARTH
• EARTH (a word common to Teutonic languages, cf. Ger. Erde, Dutch aarde, Swed. and Dan. jord; outside Teutonic it appears only in the Gr. 'pq'e, on the ground; it has been connected by some etymologists with the Aryan root ar-, to plough, which is seen in
• EARTH, FIGURE OF
• EARTH, FIGURE OF THE

earth's crust (e.g. dolomitization and silicification of many limestones) . There are also cases of metasomatism in which See also:

• STEAM
• STEAM (0. Eng. steam, vapour, smoke, cf. Du. steam; the origin is unknown)

steam and other vapours are supposed to have been operative; the temperatures were probably above the See also:

• CRITICAL (in alphabetical order of authors)

critical temperature of water . Changes of this sort are described as pneumatolytic, being induced by gases (see See also:

• PNEUMATOLYSIS (Gr. 7rvevµa, vapour, and Mete, to set free)

PNEUMATOLYSIS) . By metasomatism new minerals replace the See also:

• PRIMITIVE

primitive ones; at the same time the original rock-structures may be completely obliterated . An igneous rock for example may be entirely replaced by crystalline massive See also:

• QUARTZ

quartz, a fossiliferous limestone by granular crystalline dolomite . It is equally See also:

• COMMON

common, however, to find that the structure of the original rock is preserved though its substance has been entirely altered . An oolitic limestone may become an oolitic ironstone or chert (see PETROLOGY, Pl .

IV. fig . 5.) and casts of the fossils which the limestone contained may be formed of siderite or of See also:

• CHALCEDONY, or CALCEDONY (sometimes called by old writers cassidoine)

chalcedony . In this See also:

• CASE
• CASE, JOHN (d. 1600)

case the rock resembles a pseudomorph, which is the See also:

• TERM

term applied to a See also:

• MINERAL

mineral which has been entirely replaced by another mineral without losing its original crystalline See also:

• FORM (Lat. forma)

form . As a result of metasomatism rocks usually become more crystalline, especially those which have been in large part built up of fossil organic remains; this is a consequence of the new substances having been deposited by purely inorganic processes from solution in water . The chemical See also:

• CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change is often See also:

• COMPLETE

complete, as when a limestone is replaced by chert or otherwise silicified, but it is probably more usually incomplete, part of the substance of the original rock having been retained though possibly in new mineral combinations . When a limestone is replaced by ironstone (e.g. carbonate of See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron or siderite) part at least of the carbonic See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid may be that of the limestone . A dolomite, formed from a limestone, contains more than one-See also:

• HALF

half of its See also:

• WEIGHT

weight of carbonate of See also:

• LIME
• LIME (O. Eng. lim, Lat. limes, mud, from linere, to smear)

lime presumably derived from the limestone itself; yet in this case the mineral transformation may be perfect, as the dolomite retains none of the See also:

• CALCITE

calcite of which the lime-See also:

• STONE
• STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
• STONE, CHARLES POMEROY (1824-1887)
• STONE, EDWARD JAMES (1831-1897)
• STONE, FRANK (1800-1859)
• STONE, GEORGE (1708—1764)
• STONE, LUCY [BLACKWELL] (1818-1893)
• STONE, MARCUS (184o— )
• STONE, NICHOLAS (1586-1647)

stone was formed; it is all present as the See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double carbonate of lime and See also:

• MAGNESIA

magnesia (or dolomite) . When a See also:

• GRANITE (adapted from the Ital. granite, grained; Lat. granum, grain)

granite is converted by emanations containing See also:

• FLUORINE (symbol F, atomic weight 19)

fluorine and See also:

• BORON (symbol B, atomic weight I I)

boron into a quartz-See also:

• TOURMALINE

tourmaline rock (See also:

• SCHORL

schorl rock, q.v.) or a quartz See also:

• MICA

mica rock (See also:

• GREISEN (in French, hyalomicte)

greisen, q.v.) it can be proved by See also:

• ANALYSIS (Gr. avci and Meta, to break up into parts)

analysis that there has been very little modification of the chemical composition of the original mass . This resembles paramorphism in minerals, in which one mineral is substituted for another having the same chemical composition (e.g. kyanite for See also:

• ANDALUSITE

andalusite) . The relations between See also:

• METAMORPHISM (Gr. ise-rci, change of, and liop¢i, shape)

metamorphism and metasomatism are very See also:

• CLOSE
• CLOSE (from Lat. clausum, shut)
• CLOSE, MAXWELL HENRY (1822-1903)

close; in fact some authors regard metasomatism as a variety of metamorphism . It is generally true, however, that in metamorphic changes there is little chemical alteration; sandstones pass into quartzites, See also:

• CLAYS, PAUL JEAN (1819-1900)

clays into mica-See also:

• SCHISTS (Gr. vxq'ecv, to split)

schists and gneisses, limestones into See also:

• MARBLES

marbles without any essential modification in chemical composition, for the original minerals new ones being substituted and new structures being produced at the same time . In metasomatism, on the other- hand, chemical alteration is supposed by most geologists to be an essential feature; new minerals appear, but the original structures are sometimes retained .

The facility with which a rock undergoes metasomatism depends partly on its nature, and partly on the circumstances in which it is placed . Limestones, being readily soluble under natural conditions, are especially liable . The See also:

• CLEVELAND
• CLEVELAND (or CLEIVELAND), JOHN (1613—1658)
• CLEVELAND, BARBARA VILLIERS, DUCHESS OF (1641-1709)
• CLEVELAND, STEPHEN GROVER (1837-1908)

Cleveland iron ores of See also:

• YORKSHIRE

Yorkshire are limestones replaced by siderite and See also:

• LIMONITE, or BROWN IRON ORE

limonite; the See also:

• WHITEHAVEN

Whitehaven iron ores are metasomatic replacements of limestone by See also:

• HAEMATITE, or HEMATITE

haematite . The former are of Mesozoic, the latter of Palaeozoic See also:

• AGE (Fr. age, through late Lat. aetaticum, from aetas)

age, but both have been changed in very much the same way by percolating solutions containing salts of iron . In some cases limonite and See also:

• MAGNETITE

magnetite are the See also:

• PRINCIPAL

principal ores . Often the changes have taken place very irregularly, along bedding planes, faults and fractures . An ironstone may in many places be traced laterally into a limestone, the amount of iron in the rock gradually diminishing . Some iron-stones (Carboniferous, See also:

• JURASSIC

Jurassic, &c.) retain the oolitic structures of the original limestone ; others show See also:

• CORALS (KoRAis), ADAMANTIOS [in French, DIAMANT CORAY] (1748–1833)

corals, shells and other calca~eous fossils replaced by iron ores . When beds of shale or sandston'b are intercalated among the Limestones they usually show little change, a fact which indicates that the ready solubility of the calcareous rocks was a dominating See also:

• FACTOR (from Lat. facere, to make or do)

factor in determining the metasomatic deposits . It is believed that the Whitehaven iron ores may be derived from the ironstones of the See also:

• COAL

Coal-See also:

• MEASURES

Measures which once covered the limestone districts . Dolomitization of limestones is even more common than replacement by iron ores . That it is going on at the present See also:

• DAY (O. Eng. dreg, Ger. Tag; according to the New English Dictionary, " in no way related to the Lat. dies")
• DAY, JOHN (1574-1640?)
• DAY, THOMAS (1748-1789)

day is evident from the fact that cores obtained by See also:

• BORING

boring in See also:

• RECENT

recent See also:

• CORAL

coral reefs have shown that these may be extensively dolomitized in their deeper parts, and the older limestones such as the Triassic of the See also:

• ALPS

Alps, the Carboniferous Limestone of See also:

• ENGLAND
• ENGLAND, THE CHURCH OF

England and the See also:

• CAMBRIAN

Cambrian Limestone of See also:

• SCOTLAND
• SCOTLAND, CHURCH OF
• SCOTLAND, EPISCOPAL CHURCH OF

Scotland are sometimes converted into dolomite over wide areas .

There has been an introduction of magnesia, with sometimes a little See also:

• SILICA

silica and iron; the rock recrystallizes owing to the formation of small rhombohedra.of dolomite; it frequently becomes porous and full of drusy cavities, owing to the contraction in See also:

• VOLUME

volume which takes place, and the fossils and other organic structures of the original rock disappear . The change proceeds outwards from fissures and bedding planes and spreads gradually through the mass of the limestone; often the transformation is complete and no unaltered rock remains . Silicification or the replacement of limestone by chalcedony, chert or quartz, is often exhibited on a large See also:

• SCALE
• SCALE (1) A

scale . The formation of See also:

• FLINT
• FLINT, AUSTIN (1812-1886)
• FLINT, or FLTNTSHTRE (sir Gallestr)
• FLINT, ROBERT (1838- )
• FLINT, TIMOTHY (1780-1840)

flint nodules and chert bands is of this nature; the silica is not really an introduction from without, but is merely the material of the See also:

• FINE

fine siliceous skeletons of See also:

• SPONGES

sponges, See also:

• RADIOLARIA

radiolaria and other organisms, which at first were widely scattered through the limestone and at a later time were dissolved by percolating See also:

• WATERS, TERRITORIAL

waters, percolated through the rock and were deposited in certain situations as bands, nodules and See also:

• TABULAR

tabular masses of cryptocrystalline silica . In limestones extensive deposits of See also:

• ZINC

zinc ore may occur, usually See also:

• CALAMINE

calamine . These are important See also:

• SOURCES

sources of the See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal and there is little See also:

• ROOM

room for doubt that they have formed by a process of metasomatic replacement, e.g . Carthagena, Raibl (in See also:

• CARINTHIA (Ger. Kdrnten)

Carinthia) and See also:

• BELGIUM
• BELGIUM (Fr. Belgique; Flem. Belgic)

Belgium . In many parts of western See also:

• NORTH
• NORTH, BARONS
• NORTH, MARIANNE (1830—1890)
• NORTH, ROGER (1653-1734)
• NORTH, SIR THOMAS (1535?-16o1?)

North See also:

• AMERICA

America (See also:

• NEVADA
• NEVADA (a Spanish word meaning " snow-clad " or " snowy land," originally applied to a snow-capped mountain range on the Pacific slope)

Nevada, See also:

• ARIZONA (from the Spanish-Indian Arizonac, of unknown meaning,—possibly " few springs,"-the name of an 18th-century mining camp in the Santa Cruz valley, just S. of the present border of Arizona)

Arizona, &c.) See also:

• GREAT

great deposits of See also:

• COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper, See also:

• LEAD
• LEAD (pronounced iced)

lead and See also:

• SILVER

silver ores are worked in crystalline limestones . They are often highly silicified, and associated with them are intrusive igneous rocks such as granite, See also:

• DACITE (from Dacia, mod. Transylvania)

dacite, See also:

• PORPHYRY (IlopcPisptos) (A.D. 233-c. 304)

porphyry and See also:

• DIABASE

diabase . The ores occur not only in See also:

• VEINS

veins and shoots, but also in great masses replacing the limestone, and the geologists who have examined these See also:

• MINING

mining districts are nearly unanimous as to the metasomatic nature of a large part of these deposits . Other rocks such as See also:

• TUFF (Ital. tufo)

tuff, volcanic See also:

• BRECCIA

breccia, shale, porphyry and granite may also be impregnated with metalliferous ores, but the largest ore bodies are found in the limestones . Secondary enrichment has often taken place on a considerable scale .

The See also:

• CONSTANT, BENJAMIN (1845-1902)

constant presence of igneous rocks indicates that they are connected with the introduction of the metals, and the deposits are often of such a See also:

• KIND (O. E. ge-cynde, from the same root as is seen in " kin," supra)

kind as to show that See also:

• POST

post-volcanic discharges of magmatic gases and water have been the actual mineralizing agents . Bisbee, See also:

• CLIFTON

Clifton and the Globe See also:

• DISTRICT

district in Arizona, Flagstaff in See also:

• UTAH

Utah, and the See also:

• EUREKA

Eureka district in Nevada are See also:

• GOOD, JOHN MASON (1764-1827)

good examples of the deposits in question . As indicated above, shales, sandstones and igneous rocks may be silicified and mineralized under suitable conditions . Rhyolites and rhyolitic tuffs are often impregnated with silica to such an extent that they become almost massive quartz, and the fluidal, porphyritic, spheroidal and other igneous structures of the original rock may be retained in the siliceous pseudomorph . There are many examples of this in North See also:

• WALES (Cymru, Gwalia, Cambria)

Wales and the Pentland Hills . In andesites, serpentines and trachytes silicification is frequently found in circumstances indicating that the changes are not due to weathering but are the effect of post-volcanic emanations of heated waters . Silicified shales may accompany mineral deposits, e.g. in the Cornish See also:

• TIN (Lat.- stannum, whence the chemical symbol " Sn "; atomic weight =117.6, 0=16)

tin mines the killas or See also:

• GREY, CHARLES GREY, 2ND EARL (1764-1845)
• GREY, HENRY GREY, 3RD EARL (1802-1894)
• GREY, LADY JANE (1537-1554)
• GREY, SIR EDWARD
• GREY, SIR GEORGE (1812–1898)

grey See also:

• SLATE (properly CLAY SLATE; in M. Eng. slat or sclat, from O. Fr. esclat, a small piece of wood used as a tile; esclater, to break into pieces, whence modern Fr. eclat, the root being seen also in Ger. schleissen, to split)

slate may be converted into quartz and 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 tourmaline and contains small quantities of tin stone . In the copper mines of Parys See also:

• MOUNTAIN (0. Fr. montaigne; popular Lat. montanea, an adjectival form from the classical mons, montis, whence Eng. " mount," a form usually used along with the name of an individual mountain, e.g. Mt Everest)
• MOUNTAIN, THE (La Montagne)

Mountain, See also:

• ANGLESEY, ARTHUR ANNESLEY
• ANGLESEY, HENRY WILLIAM PAGET
• ANGLESEY, or ANGLESEA

Anglesey,' formerly of great importance as producers of this metal, there are large areas of silicified slate and silicified porphyry . 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 mica, See also:

• KAOLIN

kaolin, gilbertite, See also:

• CHLORITE

chlorite and See also:

• EPIDOTE

epidote are frequently present in silicified Igneous rocks . As a further instance of mineral deposition in metasomatized igneous rocks we may quote the Cripple See also:

• CREEK
• CREEK (Mid. Eng. crike or creke, common to many N. European languages)

Creek See also:

• GOLD
• GOLD [symbol Au, atomic weight 195.7(H = 1),197.2(0 =16)]

gold-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 in See also:

• COLORADO

Colorado, where syenites, latites, phonolites, breccias, &c., have been filled with pyrite, dolomite, fluorite, calaverite and other new minerals together with quartz . - Another type of metasomatic alteration is phosphatization . This is most common in limestones, and many of the most important bedded phosphate deposits are of this origin .

Trachytes and other igneous rocks are occasionally phosphatized . The source of the phosphate is for the most part the skeletons of animals, vertebrate bones and See also:

• TEETH (O.E. Eel); plural of tooth, O.E. top)

teeth, shells of certain brachiopods, See also:

• TRILOBITES

trilobites and other organisms . See also:

• GUANO (a Spanish word from the Peruvian huanu, dung)

Guano, the excreta of birds, is See also:

• RICH, BARNABE (c. 1540-1617)
• RICH, CLAUDIUS JAMES (1787-1821)
• RICH, JOHN (1692-1761)
• RICH, PENELOPE, LADY (c. 1562–1607)
• RICH, RICHARD, 1ST BARON RICH (1490?-1567)

rich in See also:

• PHOSPHATES

phosphates and these are washed downwards by See also:

• RAIN (O.E. regn; the word is common to Teutonic languages, cf. Ger. Regen, Swed. and Dan. regn; it has been connected with Lat. rigare, to wet, Gr. 13pixeav)

rain producing See also:

• META

meta-somatic changes in the underlying rocks . Phosphatized limestones are obtained in great quantities in See also:

• CHRISTMAS (i.e. the Mass of Christ)

Christmas See also:

• ISLAND (O.E. ieg =isle, +land')

Island, See also:

• SOMBRERO

Sombrero, Curacoa and other uninhabited limestone islands . (J . S .