ARAGONITE  , one of the See also:

• MINERAL

mineral forms of See also:

• CALCIUM [symbol Ca, atomic weight 40.0 (o= x6)]

calcium carbonate (CaCO3), the other See also:

• FORM (Lat. forma)

form being the more See also:

• COMMON

common mineral See also:

• CALCITE

calcite . It crystallizes in the orthorhombic See also:

• SYSTEM

system, and the crystals are either prismatic or acicular 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 . See also:

• SIMPLE

Simple crystals are, how-ever, rare; twinning on the See also:

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

prism planes (M in the figures) being a characteristic feature of the mineral (fig . I) . Thistwinning is usually often repeated on the same See also:

• PLANE

plane (fig . 2), and gives rise to striations on the terminal faces (k) of the crystals; often, also, three crystals are twinned together on two of the prism planes of one of them, producing an apparently hexagonal prism . The mineral is colourless, 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 or yellowish, transparent or translucent, has a vitreous lustre, and, in fact, is not unlike calcite in See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance . It may, however, always be readily distinguished from calcite by the See also:

• ABSENCE (Lat. absentia)

absence of any marked cleavage, and by its greater hardness (H.=3a-4) and specific gravity (2.93); further, it is optically biaxial, whilst calcite is uniaxial . It is brittle and has a subconchoidal fracture; on a fractured See also:

• SURFACE

surface the lustre is decidedly resinous in See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character . The mineral was first found, as reddish twinned crystals with the form of six-sided prisms, at See also:

• MOLINA, LUIS (1535-1600)

Molina in See also:

• ARAGON, or ARRAGON (in Span. Aragon)

Aragon, See also:

• SPAIN
• SPAIN (Espana)

Spain, where it occurs with See also:

• GYPSUM

gypsum and small crystals of ferruginous See also:

• QUARTZ

quartz in a red See also:

• CLAY (from O. Eng. claeg, a word common in various forms to Teutonic languages, cf. Ger. Klei)
• CLAY, CASSIUS MARCELLUS (1810-1903)
• CLAY, CHARLES (1801–1893)
• CLAY, FREDERIC (1838–1889)
• CLAY, HENRY (1777–1852)

clay . It is from this locality that the mineral takes its name, which was originally spelt arragonite . See also:

• FINE

Fine See also:

• GROUPS
• GROUPS, THEORY

groups of crystals of the same habit are found in the See also:

• SULPHUR

sulphur deposits of See also:

• GIRGENTI (anc. Agrigent'um, q.v.)

Girgenti in See also:

• SICILY (Ital. Sicilia)

Sicily; also at Herrengrund near Neusohl in See also:

• HUNGARY
• HUNGARY (Hungarian Magyarorszdg)

Hungary .

At many other localities the mineral takes the form of radiating groups of acicular crystals, such as those from the See also:

• HAEMATITE, or HEMATITE

haematite mines of See also:

• WEST
• WEST, BENJAMIN (1738-1820)
• WEST, NICHOLAS (1461-1533)

west See also:

• CUMBERLAND
• CUMBERLAND, DUKES AND EARLS OF
• CUMBERLAND, RICHARD (1632-1718)
• CUMBERLAND, RICHARD (1732-1811)
• CUMBERLAND, WILLIAM AUGUSTUS

Cumberland: beautiful feathery forms have been found in a See also:

• LIMESTONE

limestone See also:

• CAVE (Lat. cavea, from caves, hollow)
• CAVE, EDWARD (1691–1754)
• CAVE, WILLIAM (1637–1713)

cave in the See also:

• TRANSVAAL

Transvaal . Fibrous forms are also common . A See also:

• PECULIAR

peculiar coralloidal variety known as flosferri (" See also:

• FLOWER (Lat. flos, floris; Fr. fleur)
• FLOWER, SIB

flower of See also:

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

iron ") consists of radially arranged See also:

• FIBRES
• FIBRES (or FIBERS, in American spelling; from Lat. fibra, apparently connected either with filum, thread, or findere, to split)

fibres: magnificent See also:

• SNOW (in O. Eng. sndw; a common Indo-European word; cf. in Teutonic languages, Ger. Schnee, Du. sneeuw; in Slavonic snieg', Lith. snegas; Gr. vi4a, Lat. nix, nivis, whence the Romanic forms, Ital. neve, Fr. neige, &c.; Ir. and Gael. sneachd; the original

snow-white specimens of this variety have See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long been known from the iron mines of See also:

• EISENERZ (" Iron ore ")

Eisenerz in See also:

• STYRIA (German, Steiermark or Steyermark)

Styria: The calcareous secretions of many groups of invertebrate animals consist of aragonite (calcite is also common); pearls may be specially cited as an example . Aragonite is a member of the isomorphous See also:

• GROUP

group of minerals comprising See also:

• WITHERITE

witherite (BaCO3), See also:

• STRONTIANITE

strontianite (SrCO3), See also:

• CERUSSITE

cerussite (PbCO3) and See also:

• BROMLITE

bromlite ((Ba, Ca)CO3); and crystals of aragonite sometimes contain small amounts of See also:

• STRONTIUM [Symbol Sr, atomic weight 87.62 (0=16)]

strontium or See also:

• LEAD
• LEAD (pronounced iced)

lead . A-variety known as ta.rnowitzite, from Tarnowitz in See also:

• SILESIA

Silesia, contains about 5 % of lead carbonate . Aragonite is the more unstable of the two modifications of calcium carbonate . A crystal of aragonite when heated becomes converted into a granular aggregate of calcite individuals: altered crystals of this See also:

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

kind (paramorphs) are not infrequently met with in nature, whilst in fossil shells the See also:

• ORIGINAL

original nacreous layer of aragonite has invariably been altered to calcite . From a See also:

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

solution of calcium carbonate in See also:

• WATER

water containing See also:

• CARBON (symbol C, atomic weight 12)

carbon dioxide crystals of calcite are deposited at the See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary temperature, but from a warm solution aragonite crystallizes out . The thermal springs of See also:

• CARLSBAD

Carlsbad See also:

• DEPOSIT (Lat. depositurn, from deponere, to lay down, to put in the care of)

deposit spherical concretions of aragonite, forming masses known as pisolite or Sprudelstein . (L . J .