PREHNITE  , a See also:

• MINERAL

mineral consisting of See also:

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

calcium See also:

• HYDROGEN [symbol H, atomic weight x-oo8 (0=16)]

hydrogen orthosilicate, H2Ca2Al2(SiO4)3 . It crystallizes in the See also:

• HEMIMORPHIC

hemimorphic class of the orthorhombic See also:

• SYSTEM

system, but the hemimorphic See also:

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

character is usually obscured by twinning . Crystals are generally platy 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, but they rarely occur singly and distinctly shaped; almost invariably they are closely aggregated together to See also:

• FORM (Lat. forma)

form See also:

• BARREL (a word of uncertain origin common to Romance languages; the Celtic forms, as in the Gaelic baraill, are derived from the English)

barrel-shaped or globular See also:

• GROUPS
• GROUPS, THEORY

groups with a crystalline See also:

• SURFACE

surface . This form, together with the 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 oil-See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green See also:

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

colour, gives the mineral a very characteristic See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance . It is translucent and has a vitreous lustre . The hardness is rather over 6 and the spec. See also:

• GRAY
• GRAY (or GREY), WALTER DE (d. 1255)
• GRAY, ASA (1810-1888)
• GRAY, DAVID (1838-1861)
• GRAY, ELISHA (1835-1901)
• GRAY, HENRY PETERS (1819-18/7)
• GRAY, HORACE (1828–1902)
• GRAY, JOHN DE (d. 1214)
• GRAY, JOHN EDWARD (1800–1875)
• GRAY, PATRICK GRAY, 6TH BARON (d. 1612)
• GRAY, ROBERT (1809-1872)
• GRAY, SIR THOMAS (d. c. 1369)
• GRAY, THOMAS (1716-1771)

gray . 2.80–2.95 . Crystals are pyro-electric . Prehnite is sometimes classed with the See also:

• ZEOLITES

zeolites, since it occurs under the same conditions as these minerals and often in association with them: the small amount of See also:

• WATER

water (4.4%) is, however, expelled only at a red See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat and is therefore not water of See also:

• CRYSTALLIZATION

crystallization . Prehnite occurs as a mineral of secondary origin in the amygdaloidal cavities of basic igneous rocks, such as See also:

• BASALT

basalt and See also:

• DIABASE

diabase, and less often, in See also:

• VEINS

veins in See also:

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

granite and See also:

• GNEISS

gneiss . See also:

• FINE

Fine specimens are found with zeolites in the volcanic rocks of several places in the See also:

• SOUTH
• SOUTH, ROBERT (1634–1716)

south of See also:

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

Scotland, e.g . Old See also:

• KILPATRICK, NEW, or EAST
• KILPATRICK, OLD

Kilpatrick in See also:

• DUMBARTONSHIRE

Dumbartonshire, Bishopton in Renfrewshirc, Campsie Hills in See also:

• STIRLINGSHIRE

Stirlingshire and in the neighbourhood of See also:

• EDINBURGH

Edinburgh; also at See also:

• PATERSON
• PATERSON, ROBERT (1715-1801)
• PATERSON, WILLIAM (1658-1719)

Paterson and See also:

• BERGEN

Bergen 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 in New See also:

• JERSEY
• JERSEY, EARLS OF

Jersey, and with native See also:

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

copper in the See also:

• TRAP (0. Eng. treppe or traepee, properly a step, as that or which an animal places its foot and is caught, cf. Ger. Treppe flight of stairs)

trap-rocks of the See also:

• LAKE
• LAKE, GERARD LAKE, 1ST VISCOUNT (1744-1808)

Lake See also:

• SUPERIOR

Superior region .

In the See also:

• FRENCH
• FRENCH, DANIEL CHESTER (1850– )
• FRENCH, NICHOLAS (1604-1678)

French (at Le Bourg d'Oisans) and Tyrolese See also:

• ALPS

Alps it occurs with See also:

• AXINITE

axinite, See also:

• EPIDOTE

epidote, See also:

• FELSPAR, or FELDSPAR

felspar, &c., lining crevices in gneiss . Large masses have been found at Credock in Cape See also:

• COLONY (Lat. colonia, from colonus, a cultivator)

Colony, from which locality it was brought in the 18th See also:

• CENTURY (from Lat. centuria, a division of a hundred men)

century by See also:

• COLONEL (derived either from Lat. column, Fr. colonne, column, or Lat. corona, a crown)

Colonel Prehn, the See also:

• GOVERNOR (from the Fr. gouverneur, from gouverner, O. Fr. governer, Lat. gubernare, to steer a ship, to direct, guide)

governor of the colony; hence the names " Cape See also:

• CHRYSOLITE

chrysolite " and prehnite (of A . G . See also:

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

Werner, 1789) . Prehnite is sometimes cut and polished for small ornaments; it then somewhat resembles See also:

• CHRYSOPRASE (Gr. Xpvvor, gold, and apaorov, leek)

chrysoprase in appearance .