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TALC , a See also:mineral which in its compact forms is known as steatite, or soapstone. It was probably the µayvitres A Wos of See also:Theophrastus, described as a See also:- STONE
- STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
- STONE, CHARLES POMEROY (1824-1887)
- STONE, EDWARD JAMES (1831-1897)
- STONE, FRANK (1800-1859)
- STONE, GEORGE (1708—1764)
- STONE, LUCY [BLACKWELL] (1818-1893)
- STONE, MARCUS (184o— )
- STONE, NICHOLAS (1586-1647)
stone of silvery lustre, easily
cut. The word talc, sometimes written talk, is said to come from the Arabic talc, and not to be connected, as has been fancifully suggested, with the See also:Swedish talja, " to cut." Talc and See also:mica were confused by the older writers, and even at the See also:present See also:day mica is sometimes known in See also:trade as talc; whilst the See also:term was formerly applied also to foliated See also:gypsum.
Talc is found occasionally in small hexagonal and rhombic plates, with perfect basal cleavage, and they are supposed to be See also:monoclinic. Talc often occurs in foliated masses, sometimes with a curved See also:surface, readily separating into thin very flexible, non-elastic laminae. The plates give a six-rayed percussion-figure. Talc has a hardness of only about r, and a specific gravity of from 2.6 to 2.8. Its extreme softness and its greasy feel are characteristic. The lustre on the cleavage See also:face is pearly, or sometimes silvery, and one of the old names of the mineral was stella terrae, while See also:German writers sometimes called it Katzensilber. The See also:colour is 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, See also:grey, yellow or frequently See also:green. The mineral has strong birefringence and a small optic axial See also:angle.
Talc is a See also:magnesium silicate H2Mg3Si4O12. It is generally regarded as a hydrous silicate, but the See also:water is expelled only at a very strong See also:heat, and may therefore be regarded as basic. By the See also:action of heat the hardness of the mineral is greatly increased. Pseudomorphs are known after actinolite, See also:pyroxene, &c., and the mineral has probably been generally formed by the alteration of ferro-magnesian silicates. Talc occurs chiefly in crystalline See also:schists, usually associated with See also:chlorite, See also:serpentine and See also:dolomite. See also:Fine examples of See also:apple-green colour are found at See also:Mount Greiner, in the Zillerthal, See also:Tirol. Talc-schist is a foliated See also:rock composed chiefly of talc, generally associated with See also:quartz and See also:felspar; but all soapy schists are not necessarily talcose. The pearly micaceous constituent of the Alpine protogine is a See also:muscovite.
The " steatites " of See also:Pliny was a stone resembling See also:fat, but other-See also:wise undescribed. Being easily cut, steatite has always been a favourite material with the See also:carver: it was used for See also:Egyptian scarabs and other amulets, which were usually coated with a See also:blue vitreous glaze; and it was employed for See also:Assyrian See also:cylinder-See also:seals and for other See also:ancient signets. By the See also:Chinese steatite is largely used for ornamental carvings, but many of their " See also:soap-stone " figures are wrought in a compact See also:pyrophyllite (q.v.), which is essentially different from talc. The name agalmatolite is often applied to the material of these figures, and was suggested by M. H. See also:Klaproth from the See also:Greek ayaXpa, " an See also:image." Pagodite is an old name for Chinese figure-stone. Ancient steatite carvings are found among the ruins of See also:Rhodesia.
Steatite is usually a white, grey, greenish or 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 substance, occurring in See also:veins or nodular masses or in lenticular bedded deposits. Pseudomorphs after quartz and dolomite occur near Wunsiedel in See also:Bavaria. In some cases it is a product of the alteration of pyroxenic rocks, and the commercial mineral may be very impure. The ease with which steatite may be worked, coupled with its See also:power of resisting heat, has led to its employment for vessels for See also:household use, whence it is called " potstone "—the lapis ollaris of old writers. Among the uses of steatite may be mentioned its employment, especially in See also:America, for sinks, stoves, firebricks, See also:foot-warmers, tips for See also:gas-burners and electric switchboards: when ground it is used as a filler for See also:paper, for See also:leather-dressing, for covering See also:steam-pipes, as an ingredient in soap, for See also:toilet-See also:powder, for certain paints and as a lubricant. A fine granular steatite is used by tailors for marking See also:cloth under the name of " See also:French See also:chalk " or " See also:Spanish chalk." See also:Slate pencils are made of steatite and pyrophyllite; and in See also:Burma steatite pencils are used for See also:writing on See also:black paper. In the oxyhydrogen See also:flame, steatite has been fused and See also:drawn out into threads, like quartz-See also:fibres.
Steatite and talc-schists are widely distributed, and have occasion-ally been used as See also:building stones. When first raised the stone is soft, but hardens on exposure. Soapstone from See also:Gudbrandsdal is used in the See also:cathedral of See also:Trondhjem in See also:Norway.
Veins of steatite occur in the serpentine of the See also:Lizard See also:district in See also:Cornwall, and the mineral was used under the name of soap rock in the manufacture of the old See also:Worcester See also:porcelain. Among localities of steatite369
in the See also:British Isles mention may be made of Crohy See also:Head and Gartan near See also:Letterkenny in co. See also:Donegal, See also:Ireland; the See also:Shetland isles, the See also:Hebrides (See also:Harris) and Shiness in See also:Sutherland. In See also:North America the See also:distribution of the mineral is very extensive; localities of economic importance are near Gouverneur and elsewhere in St See also:- LAWRENCE
- LAWRENCE (LAURENTIUS, LORENZO), ST
- LAWRENCE, AMOS (1786—1852)
- LAWRENCE, AMOS ADAMS (1814–1886)
- LAWRENCE, GEORGE ALFRED (1827–1876)
- LAWRENCE, JOHN LAIRD MAIR LAWRENCE, 1ST BARON (1811-1879)
- LAWRENCE, SIR HENRY MONTGOMERY (1806–1857)
- LAWRENCE, SIR THOMAS (1769–1830)
- LAWRENCE, STRINGER (1697–1775)
Lawrence co., New See also:York; at Francestown in New See also:Hampshire; See also:Stockbridge, See also:Windsor co., See also:Vermont; Lynnfield, See also:Massachusetts; near See also:Lafayette, See also:Pennsylvania; See also:Albemarle, Amelia, See also:- BUCKINGHAM
- BUCKINGHAM, EARLS, MARQUESSES AND DUKES OF
- BUCKINGHAM, FIRST DUKE
- BUCKINGHAM, GEORGE VILLIERS, 1ST DUKE 0E1
- BUCKINGHAM, GEORGE VILLIERS, 2ND DUKE 0E1 (1628-1687)
- BUCKINGHAM, HENRY STAFFORD, 2ND DUKE OF3 (1454-1483)
- BUCKINGHAM, JAMES SILK (1786-1855)
Buckingham, See also:Fairfax and Fluvanna See also:cos., See also:Virginia; See also:Cherokee, See also:Moore and Swain cos., North Carolina; and in See also:- MURRAY
- MURRAY (or MORAY), EARLS OF
- MURRAY (or MORAY), JAMES STUART, EARL OF (c. 1531-1570)
- MURRAY (or MORAY), SIR ROBERT (c. 1600-1673)
- MURRAY, ALEXANDER STUART (1841-1904)
- MURRAY, DAVID (1849– )
- MURRAY, EUSTACE CLARE GRENVILLE (1824–1881)
- MURRAY, JAMES (c. 1719-1794)
- MURRAY, JOHN
- MURRAY, JOHN (1778–1820)
- MURRAY, LINDLEY (1745–1826)
- MURRAY, LORD GEORGE (1694–1760)
- MURRAY, SIR JAMES AUGUSTUS HENRY (1837– )
- MURRAY, SIR JOHN (1841– )
Murray co., See also:Georgia.
A fibrous steatite from New York See also:state, used in the manufacture of paper, is known as agalite. Rensselaerite is a See also:wax-like talcose substance, passing into serpentine, from St Lawrence co., New York, named by E. See also:Emmons in 1837 after S. See also:Van See also:Rensselaer, of See also:Albany, N.Y. Beaconite is an asbestiform talc from See also:Michigan, named by L. W. Hubbard. The term pyrallolite was given by Nils G. See also:Nordenskiold to a mineral from See also:Finland, which appears to be talc pseudomorphous after pyroxene. Talcoid was K. F. See also:Naumann's name for a white lamellar mineral from near Pressnitz in Bohemia. A blue earthy mineral from near See also:Silver See also:City, New See also:Mexico, known locally as " native See also:ultramarine," is a magnesium silicate.
See " '1ilr1c and Soapstone " in vol. ii. of Mineral Resources of the U.S. (See also:Washington, 1909), and J. H. See also:Pratt, " Economic Papers," No. 3 of Geol. Surv. of N. Carolina (1900) ; also E. W. See also:Parker in 19th See also:Report of U.S. Geol. Surv. (1898) ; C. H. See also:Smyth, junior, The Fibrous Talc See also:Industry of St Lawrence Co., N.Y., in " Mineral Industry," vol. ix., for 1900; and G. P. See also:Merrill's Non-metallic Minerals (New York, 1904). (F. W.
End of Article: TALC
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