See also:

• DIORITE (from the Gr. S&oi4eiv to distinguish, from hA through, Epos, a boundary)

DIORITE (from the Gr. S&oi4eiv to distinguish, from hA through, Epos, a boundary)  , in See also:

• PETROLOGY

petrology, the name given by See also:

• HAUY, RENE JUST (1743-1822)

Hauy to a See also:

• FAMILY

family of rocks of granitic texture, composed of See also:

• PLAGIOCLASE

plagioclase See also:

• FELSPAR, or FELDSPAR

felspar and See also:

• HORNBLENDE

hornblende . As they are richer in the dark Viii . IOcoloured ferromagnesian minerals they are usually 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 or dark grey, and have a higher specific gravity than See also:

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

granite . They also rarely show visible See also:

• QUARTZ

quartz . But there are diorites of many kinds, as the name applies rather to a family of rocks than to a single See also:

• SPECIES

species . Some contain See also:

• BIOTITE

biotite, others See also:

• AUGITE

augite or See also:

• HYPERSTHENE

hypersthene; many have a small amount of quartz . See also:

• ORTHOCLASE

Orthoclase is rarely entirely absent, and when it is fairly See also:

• COMMON

common the 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 becomes a See also:

• TONALITE

tonalite; in this way a transition is furnished between diorites and granites . It is rare to find the pure types of " hornblende-See also:

• DIORITE (from the Gr. S&oi4eiv to distinguish, from hA through, Epos, a boundary)

diorite," " augite-diorite," &c., but in most cases the rocks contain two or more ferromagnesian silicates, and such combinations as " hornblende-biotite-diorite " are commonest in nature . The felspar of the diorites ranges in See also:

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

composition from See also:

• OLIGOCLASE

oligoclase to See also:

• LABRADORITE, or LABRADOR SPAR

labradorite, and is often remarkably zonal, the See also:

• EXTERNAL

external layers being more alkaline than the See also:

• INTERNAL

internal . Small fluid enclosures and See also:

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

black: gains, probably See also:

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

iron oxides, often occur in it in See also:

• GREAT

great See also:

• NUMBERS, BOOK OF
• NUMBERS, PARTITION OF

numbers . Weathering produces See also:

• EPIDOTE

epidote, See also:

• CALCITE

calcite, sericite and See also:

• KAOLIN

kaolin . The biotite is always 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 or yellow; the hornblende usually 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, but sometimes brown or yellowish brown in those diorites which have See also:

• AFFINITIES

affinities to See also:

• LAMPROPHYRES (from Gr. Xaurp6s, bright, and the terminal part of the word porphyry, meaning rocks containing bright porphyritic crystals)

lamprophyres .

The augite is nearly always green but sometimes has a reddish tinge; See also:

• BRONZITE

bronzite and hypersthene have their usual green and brown shades . See also:

• APATITE

Apatite, iron oxides and See also:

• ZIRCON

zircon are almost invariably See also:

• PRESENT

present; See also:

• SPHENE

sphene, See also:

• GARNET
• GARNET, or GARNETT, HENRY (1555—1606)

garnet and orthite are occasionally observed; calcite, See also:

• CHLORITE

chlorite, See also:

• MUSCOVITE

muscovite, kaolin, epidote and bastite are secondary . The structure is not essentially different from that of granite . The ferromagnesian minerals crystallize comparatively See also:

• EARLY
• EARLY, JUBAL ANDERSON (1816-1894)

early and have some idiomorphism; the felspar usually follows and only in See also:

• PART

part shows See also:

• GOOD, JOHN MASON (1764-1827)

good crystalline outlines . Orthoclase and quartz, if present, are last to See also:

• SEPARATE

separate out, and fill the spaces between the other minerals; often they interpenetrate to See also:

• FORM (Lat. forma)

form micropegmatite . In many diorites the plagioclase felspar has crystallized before the hornblende, which consequently has less perfect outlines and forms irregular plates which enclose sharply formed individuals of felspar . This produces the ophitic structure (very common also in the dolerites) . More rarely biotite and augite exhibit the same relations to the plagioclase . Orbicular structure also occasionally appears in these rocks; in fact the orbicular diorite of See also:

• CORSICA (Fr. Corse)

Corsica (also called " See also:

• NAPOLEONITE

Napoleonite " or " Corsite ") was for a See also:

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

long 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 the best-known example of this structure . The rock seems composed of spheroids, about an See also:

• INCH (O. Eng. ynce from Lat. uncia, a twelfthpart; cf. " ounce," and see As)

inch in See also:

• DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter, surrounded by a smaller amount of dark-coloured dioritic See also:

• MATRIX

matrix . The spheroids have a radiate structure and often show concentric dark and 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 shells . These consist of hornblende (dark green) and basic plagioclase felspar, labradorite and See also:

• BYTOWNITE

bytownite (grey or nearly 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) .

Occasionally diorites have a parallel banded or foliated structure, but these must not be confounded with the epidiorites, which are metamorphic rocks and also have a conspicuous foliation . Diorites must also he distinguished from hornblendic gabbros, which contain more basic felspars, rarely quartz and occasionally See also:

• OLIVINE

olivine; but the boundary lines between diorites and gabbros are admittedly somewhat vague, e.g. some authors would See also:

• CALL (from Anglo-Saxon ceallian, a common Teutonic word, cf. Dutch kallen, to talk or chatter)

call rocks See also:

• GABBRO

gabbro which others would regard as augite-diorite . The hornblendites differ from the diorites in containing little felspar, and consist principally of hornblende . Among varietal designations given to rocks of the diorite family are " banatite " for an augitediorite with or without quartz (from the Schemnitz See also:

• DISTRICT

district), " granodiorite " for a quartz-hornblende-diorite (essentially the same as tonalite) from See also:

• CALIFORNIA
• CALIFORNIA, LOWER (Baja California)
• CALIFORNIA, UNIVERSITY OF

California, &c., " adamellite " for the quartz-See also:

• MICA

mica-diorite or tonalite of See also:

• MONTE

Monte Adamello (See also:

• ALPS

Alps), " ornite " for a hornblende-diorite 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 felspar, from See also:

• SWEDEN
• SWEDEN [Sverige]
• SWEDEN, NORWAY AND

Sweden . (J . S .