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 primary quartz, and are the most siliceous members of the family; their quartz may appear in small blebs (or phenocrysts), or may occur only as minute interstitial grains in the groundmass; other dacites are very vitreous (dacitic-pitchstones). In many of their structural peculiarities they closely simulate the rhyolites, from which they differ in containing less potash and more soda, and in consequence less orthoclase felspar and more plagioclase. The hornblende- and biotite-andesites, like the dacites, have in most cases a pale colour (pink, yellow or grey), being comparatively rich in felspar. They resemble the trachytes both in appearance and in structure, but their felspar is mostly plagioclase, not sanidine. The biotite and hornblende have much the same characters in both of these groups of rocks, and are often surrounded by black borders produced by corrosion and partial resorption by the magma. A pale green augite is common in these andesites, but bronzite or hypersthene is comparatively rare. The pyroxene-andesites are darker, more basic rocks, with a higher specific gravity, and approach closely to the basalts and dolerites, especially when they contain a small amount of olivine. They are probably the commonest types of andesite, both at the present time and in former geological periods. Often their groundmass consists of brownish glass, filled with small microliths of augite and felspar, and having a velvety, glistening lustre when observed in a good light (hyalopilitic structure).

In addition to the accessory minerals, zircon, apatite and iron oxides, which are practically never absent, certain others occur which, on account of their rarity and importance, are of special interest. Sharply-formed little crystals of cordierite are occasionally found in andesites (Japan, Spain, St Vincent, Cumberland); they seem to depend on more or less complete digestion of fragments of gneiss and other rocks in the molten lava. Garnet and sapphire have also been found in andesites, and perhaps have the same signification; a rose-red variety of epidote (withamite) is known as a secondary product in certain andesites (Glencoe, Scotland), and the famous red porphyry (porfido rosso) of the ancients is a rock of this type. Ore deposits very frequently occur in connexion with andesitic rocks (Nevada, California, Hungary, Borneo, &c.), especially those of gold and silver. They have been laid down in fissures as veins of quartz, and the surrounding igneous rocks are frequently altered and decomposed in a peculiar way by the hot ascending metalliferous solutions. Andesites affected in this manner are known as propylites. The alteration is one of those post-volcanic, pneumatolytic processes, so frequent in volcanic districts. Propylitization consists in the replacement of the original minerals of the andesite by secondary products such as kaolin, epidote, mica, chlorite, quartz and chalcedony, often with the retention of the igneous structures of the rocks.

In microscopic characters the andesites present considerable variety; their porphyritic felspars are usually of tabular shape with good crystalline outlines, but often filled with glass enclosures. Zonal structure is exceedingly common, and the central parts of the crystals are more basic (bytownite, &c.) than the edges (oligoclase). Sanidine occurs with considerable frequency, but not in notable amount. The biotite and hornblende are yellow or brown and richly pleochroic. The hypersthene is nearly always idiomorphic, with a distinct pleochroism ranging from salmon-pink to green. Augite may be green in the more acid andesites, but is pale brown in the pyroxene-andesites. The apatite is often filled with minute dust-like enclosures. In the dacites felsitic groundmasses are by no means rare, but micro-crystalline types consisting of plagioclase and sanidine with quartz are more prevalent. The hornblende- and mica-andesites have groundmasses composed mainly of acid plagioclase with little orthoclase or glassy base (pilotaxitic groundmass). Clear brown glass with many small crystals of plagioclase and pale brown augite (hyalopilitic groundmass) is very frequent in pyroxene-andesites. Vitreous rocks belonging to all of the above groups are well known though not very common, and exhibit the perlitic, pumiceous, spherulitic and other structures, characteristic to volcanic obsidians and pitchstones.

ANDIJAN, a town of Russian Turkestan, Province of Ferghana, eastern terminus of the Transcaspian railway, 84 m. by rail E.N.E. of Khokand, on the left bank of the upper Syr-darya. Altitude 1630 ft. Pop. (1900) 49,682. It was formerly the residence of the khans of Khokand, and has beautiful gardens and a large park in the middle of the town. Andijan is a centre for the trade in raw cotton and has cotton factories. All over Central Asia, West Turkestan merchants are known generally as Andijani. The town was destroyed by an earthquake on the 16th-17th of December 1902, when 5000 persons perished and 16,000 houses were demolished. It has since been rebuilt. ANDIRON (older form anderne; med. Lat. andena, anderia), a horizontal iron bar, or bars, upon which logs are laid for burning in an open fireplace. Andirons stand upon short legs and are usually connected with an upright guard. This guard, which may be of iron, steel, copper, bronze, or even silver, is often elaborately ornamented with conventional patterns or heraldic ornaments, such as the fleur-de-lys, with sphinxes, grotesque animals, mythological statuettes or caryatides supporting heroic figures or emblems. Previously to the Italian Renaissance, andirons were almost invariably made entirely of iron and comparatively plain, but when the ordinary objects of the household became the care of the artist, the metal-worker lavished skill and taste upon them, and even such a man as Jean Bérain, whose fancy was most especially applied to the ornamentation of Boulle furniture, sometimes designed them. Indeed the fire-dog or chenet reached its most artistic development under Louis XIV. of France, and the first extant examples—often of cast-iron—are to be found in French museums and royal palaces. Fire-dogs, with little or no ornament, were also used in kitchens, with ratcheted uprights for the spits. Very often these uprights branched out into arms or hobs for stewing or keeping the viands hot. ANDKHUI, a town and khanate in Afghan Turkestan. The town (said to have been founded by Alexander the Great) stands between the northern spurs of the Paropamisus and the Oxus; it is 100 m. due west of Balkh on the edge of the Turkman desert. The khanate is of importance as being one of the most northern in Afghanistan, on the Russian border. Until 1820 it was subject to Bokhara, but in that year Mahmud Khan besieged it for four months, took it by storm and left it a heap of ruins. To preserve himself from utter destruction the khan threw himself into the arms of the Afghans. The tract in which Andkhui stands is fertile, but proverbially unhealthy; the Persians account it “a hell upon earth” by reason of its scorching sands, brackish water, flies and scorpions. The population, estimated at 15,000, consists principally of Turkmans with a mixture of Uzbegs and a few Tajiks. The district was allotted to Afghanistan by the Russo-Afghan boundary commission of 1885. ANDOCIDES, one of the “ten” Attic orators, was born about 440 Implicated in the mutilation of the Hermae (415), although he saved his life by turning informer, he was condemned to partial loss of civil rights and went into exile. He engaged in commercial pursuits, and after two unsuccessful attempts returned to Athens under the general amnesty that followed the restoration of the democracy (403), and filled some important offices. In 391 he was one of the ambassadors sent to Sparta to discuss peace terms, but the negotiations failed, and after this time we hear no more of him. Oligarchical in his sympathies, he offended his own party and was distrusted by the democrats. Andocides was no professional orator; his style is simple and lively, natural but inartistic.

ANDORRA, or, a small, neutral, autonomous, and semi-independent state, on the Franco-Spanish frontier, and chiefly on the peninsular side of the eastern Pyrenees. Pop. (1900) about 5500; area about 175 sq. m. Andorra is surrounded