RUTILE  , the most abundant of the three native forms of See also:

• TITANIUM [symbol Ti, atomic weight 48.1 (0 = 16)]

titanium dioxide (TiO2) ; the other forms being See also:

• ANATASE

anatase (q.v.) and See also:

• BROOKITE

brookite (q.v.) . Like anatase, it crystallizes in the tetragonal See also:

• SYSTEM

system, but with different angles and cleavages, it being crystallographically related to cassiterite, with which it is isomorphous . The crystals resemble cassiterite in their prismatic See also:

• HABIT (through the French from Lat. habitus, from habere, to have, hold, or, in a reflective sense, to be in a certain condition; in many of the English senses the French use habitude, not habit)

habit and terminal See also:

• PYRAMID

pyramid planes (fig . I) and also in the twinning: the See also:

• PRISM (Gr. rrpivµa, properly a thing sawn, Irpii"ety, to saw)

prism planes are striated vertically . Geniculated twins, with e (ior) as twin-See also:

• PLANE

plane, are of frequent occurrence, and the twinning is usually several times repeated, giving rise to triplets (fig . 2), sextets and octets . Twin-lamellae are often See also:

• PRESENT

present in the crystals . Acicular crystals are sometimes twinned together to See also:

• FORM (Lat. forma)

form reticulated skeletal plates to which the name " sagenite," from Gr. oayi7vn (a See also:

• NET

net), is applied . A rarer type of twinning, on the plane (301), gives rise to See also:

• HEART
• HEART, LUNG

heart-shaped or See also:

• KITE

kite-shaped forms . There are distinct cleavages parallel to the faces of the prisms m (110) and a (See also:

• LOO (formerly called " Lanterloo," Fr. lanturlu, the refrain of a popular 17th-century song)

loo) . The See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour is usually reddish-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, though yellowish in the very See also:

• FINE

fine needles, and See also:

• BLACK
• BLACK, ADAM (1784-1874)
• BLACK, JEREMIAH SULLIVAN (1810–1883)
• BLACK, WILLIAM (1841-1898)

black in the ferruginous varieties (" nigrine " and " ilmeno See also:

• RUBLE

ruble "): the streak is See also:

• PALE (through Fr. pal, from Lat. palms, a stake, for paglus, from the stem pag- of pangere, to fix; " pole " is from the same original source)

pale brown . The name rutile, given by A .

G . See also:

• WERNER, ABRAHAM GOTTLOB (1750-1817)
• WERNER, ANTON ALEXANDER VON (1843– )
• WERNER, FRIEDRICH LUDWIG ZACHARIAS (1768–1823)

Werner in 1803, refers to the colour, being from the Latin rutilus (red) . Crystals are transparent to opaque, and have a brilliant metallic-adamantine lustre . The hardness is 6a and the specific gravity 4.2, ranging, however, up to 5.2 in varieties containing Io% of ferric See also:

• OXIDE

oxide . The refractive indices and the See also:

• POSITIVE (or PORTABLE) ORGAN

positive birefringence are high . Rutile occur's as a See also:

• PRIMARY

primary constituent in eruptive rocks, but more frequently in schistose rocks . As delicate acicular crystals it is often enclosed in See also:

• MICA

mica and See also:

• QUARTZ

quartz: in mica (q.v.) it gives rise to the phenomenon of asterism; and clear transparent quartz (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-crystal) enclosing rutile is often cut as a See also:

• GEM (Lat. gemma, a bud,—from the root gen, meaning " to produce,"—or precious stone; in the latter sense the Greek term is > d>os)
• GEM, ARTIFICIAL

gem under the name of " See also:

• VENUS

Venus' See also:

• HAIR (a word common to Teutonic languages)

hair 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 " (Veneris crinis of See also:

• PLINY, THE ELDER
• PLINY, THE YOUNGER

Pliny) . Larger crystals occur in the cavities of See also:

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

granite and crystalline See also:

• SCHISTS (Gr. vxq'ecv, to split)

schists; very large twinned crystals have been found at See also:

• GRAVES, ALFRED PERCEVAL (1846— )

Graves 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 in See also:

• LINCOLN
• LINCOLN, ABRAHAM (1809-1865)
• LINCOLN, EARLS OF

Lincoln See also:

• COUNTY (through Norm. Fr. comae, cf. O. Fr. cunte, conk', Mod. Fr. comae, from Lat. comitatus, cf. Ital. comitato, Prov. comtat; see COUNT)

county, See also:

• GEORGIA

Georgia, and See also:

• GOOD, JOHN MASON (1764-1827)

good specimens have been obtained from several places in See also:

• NORWAY
• NORWAY (Norge)

Norway and the Swiss and Ti:olese See also:

• ALPS

Alps . As a secondary See also:

• MINERAL

mineral, rutile in the form of See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute needles is of wide See also:

• DISTRIBUTION (Lat. distribuere, to deal out)

distribution in various sedimentary rocks, especially See also:

• CLAYS, PAUL JEAN (1819-1900)

clays and slates . As rounded grains it is often met with in auriferous sands and gravels . The mineral has little economic value: it has been used for imparting a yellow colour to See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass and See also:

• PORCELAIN

porcelain. and for this purpose is See also:

• MINED

mined at Risor and other places in Norway: (L . J .