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ANATASE

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Originally appearing in Volume V01, Page 920 of the 1911 Encyclopedia Britannica.

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ANATASE , one of the three See also:

MINERAL

mineral forms of See also:

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

titanium dioxide. It is always- found as small, isolated and sharply See also:

DEVELOPED

developed crystals, and like See also:

RUTILE

rutile, a more commonly occurring modification of titanium dioxide, it crystallizes in the tetragonal See also:

SYSTEM

system; but, although the degree of symmetry is the same for both, there is no relation between the interfacial angles of the two minerals, except, of course, in the See also:

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

prism-See also:

ZONE (Gr. 'WV77, a girdle, from 'wvvLvay to gird)

zone of 450 and 9o°. The See also:

COMMON

common See also:

PYRAMID

pyramid {III} (fig. I) of anatase,' parallel to the faces of which there are perfect cleavages, has an See also:

ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle over the polar edge of 82° 9', the corresponding angle (III): (i11) of rutile being 56° 522'. It was on See also:

account of this steeper pyramid of anatase that the mineral was named, by R. J. Haiiy in 18oi, from the Gr. avaravls, " See also:

EXTENSION (Lat. ex, out ; tendere, to stretch)

extension," the See also:

VERTICAL (from Lat. vertex, highest point)

vertical' See also:

AXIS (Lat. for " axle ")

axis of the crystals being longer than in rutile. There are also important See also:

DIFFERENCES, CALCULUS OF (Theory of Finite Differences)

differences ' For the notation see See also:

CRYSTALLOGRAPHY. between the See also:

PHYSICAL

physical characters of anatase and rutile; the former is not quite so hard (H=54-6) or dense (sp. gr.=3.9); it is optically negative, rutile being See also:

POSITIVE (or PORTABLE) ORGAN

positive; and its lustre is even more strongly adamantine or metallic-adamantine than that of rutile. Two types or habits of anatase crystals may be distinguished. The commoner occurs as See also:

SIMPLE

simple acute See also:

double pyramids { See also:

Ill} (fig. r) with an See also:

INDIGO (earlier indico, from Lat. indicum, the Indian sub-stance or dye; the Sans. name was niti, from nila, dark blue, and this through Arab. al-nil, annil, gives " aniline ")

indigo-See also:

BLUE (common in different forms to most European languages)

blue to See also:

black See also:

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

colour and steely lustre.

Crystals of this See also:

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

kind are abundant at Le Bourg d'Oisans in See also:

DAUPHINE

Dauphine, where they are associated with See also:

rock-crystal, See also:

FELSPAR, or FELDSPAR

felspar and See also:

AXINITE

axinite in crevices in See also:

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

granite and See also:

MICA

mica-schist. Similar crystals, but of microscopic See also:

SIZE

size, are widely distributed in sedimentary rocks, such as sandstones, See also:

CLAYS, PAUL JEAN (1819-1900)

clays and slates, from which they may be separated by washing away the lighter constituents of the powdered rock. Crystals of the second type have numerous pyramidal faces developed, and they are usually flatter or sometimes prismatic in 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 (fig. 2); the colour is See also:

HONEY (Chin. me ; Sansk. madhu, mead, honey; cf. A.S. medo, medu, mead; Gr. p Xt, in which 0 or b is changed into X; Lat. mel ; Fr. miel ; A.S. hung ; Ger. Honig)

honey-yellow to See also:

brown. Such crystals closely resemble xenotime in See also:

APPEARANCE (from Lat. apparere, to appear)

appearance and, indeed, were for a See also:

long See also:

time supposed to belong to this See also:

SPECIES

species, the See also:

SPECIAL

special name wiserine being applied to them. They occur attached to the walls of crevices in the gneisses of the See also:

ALPS

Alps, the Binnenthal near See also:

BRIEG

Brieg in See also:

canton See also:

VALAIS (Ger. Wallis, Ital. Vallese)

Valais, See also:

SWITZERLAND

Switzerland, being a well-known locality. When strongly heated, anatase is converted into rutile, changing in specific gravity to 4.1; naturally occurring pseudo-morphs of rutile after anatase are also known. Crystals of anatase have been artificially prepared by several methods; for instance, by the interaction of See also:

steam and titanium chloride or fluoride. Another name commonly in use for this mineral is octahedrite, a name which, indeed, is earlier than anatase, and given because of the common (acute) octahedral habit of the crystals. Other names, now obsolete, are oisanite and dauphinite, from the well-known See also:

French locality. (L. J.

End of Article: ANATASE

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