TONALITE  , in See also:

• PETROLOGY

petrology, a 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 of the See also:

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

diorite class, first described from See also:

• MONTE

Monte Adamello near Tonale in the Eastern See also:

• ALPS

Alps . It may be described as a See also:

• QUARTZ

quartz-diorite containing See also:

• BIOTITE

biotite and See also:

• HORNBLENDE

hornblende in nearly equal proportions . The See also:

• PRINCIPAL

principal See also:

• FELSPAR, or FELDSPAR

felspar is See also:

• PLAGIOCLASE

plagioclase, but See also:

• ORTHOCLASE

orthoclase occurs also, usually in small amount . Those varieties which are 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 orthoclase, in addition to plagioclase, have been called quartz-monzonites or adamellites, but a better See also:

• TERM

term is grano-diorite, which has been very generally adopted in See also:

• AMERICA

America for rocks which are intermediate in See also:

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

character between the granites and the diorites . The hornblende of the diorites is 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, sometimes with a tinge of 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; the biotite is always brown and strongly pleochroic . Often these two minerals are clustered together irregularly or in parallel growths . They have generally a fairly strong tendency to idiomorphism, but may sometimes enclose plagioclase felspar in ophitic manner . Both of them decompose to See also:

• CHLORITE

chlorite, See also:

• EPIDOTE

epidote and See also:

• CARBONATES

carbonates . The plagioclase felspar, which may See also:

• FORM (Lat. forma)

form more than one-See also:

• HALF

half of the rock, is See also:

• ANDESINE

andesine or See also:

• OLIGOCLASE

oligoclase; See also:

• SIMPLE

simple crystals are rare, the See also:

• MAJORITY (Fr. majorite; Med. Lat. majoritas; Lat. major, greater)

majority being complex growths with centres of felspar rich in See also:

• LIME
• LIME (O. Eng. lim, Lat. limes, mud, from linere, to smear)

lime, while in the See also:

• EXTERNAL

external zones the proportion of soda felspar increases greatly . The inner portions have often well-defined, but very irregular, boundaries, and are sometimes sponge-like, with the cayities filled up with a later, more See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid, See also:

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

deposit . This seems to indicate that growth has taken See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place in stages, alternating with periods when the crystallized felspar was eroded or partly dissolved . The orthoclase sometimes forms irregular plates enclosing individuals of plagioclase .

Quartz occurs both in irregular simple grains and as micropegmatite . Occasionally 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 green See also:

• PYROXENE

pyroxene is visible in the centre of crystals of dark green hornblende . The See also:

• ACCESSORY

accessory minerals See also:

• APATITE

apatite, See also:

• MAGNETITE

magnetite and See also:

• ZIRCON

zircon are always See also:

• PRESENT

present, and very See also:

• COMMON

common also are orthite in See also:

• COFFEE (Fr: cafe, Ger. Kaffee)

coffee-coloured zonal prisms practically always encircled by yellow epidote, and reddish-brown crystals of See also:

• SPHENE

sphene, simple or twinned . In external See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance the tonalites are very like the granites but usually darker in See also:

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

colour . Tonalite-porphyrites often accompany them, having the same See also:

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

composition but with phenocrysts of felspar, quartz, hornblende and biotite in a See also:

• FINE

fine-grained ground-See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass . See also:

• VEINS

Veins and threads of fine 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 rock, mainly composed of quartz and felspar, often intersect tonalite-masses and have been called tonalite-aplites, seeing that they See also:

• BEAR
• BEAR, BLACK
• BEAR, BROWN
• BEAR, GRIZZLY
• BEAR, ISABELLINE
• BEAR, WHITE

bear the same relations to aplites as the aplites do to the granites . They contain more soda-lime felspar than the normal aplites . Towards their margins the larger alpine masses of tonalite often assume banded or gneissic facies, due apparently to See also:

• MOVEMENT

movement during intrusion .