CALAMINE  , a

mineral species consisting of zinc carbonate, ZnCO3, and forming an important ore of zinc . It is rhombohedral in crystallization and isomorphous with calcite and chalybite . Distinct crystals are somewhat rare; they have the form of the primitive rhombohedron ('=72° 20'), the faces of which are generally curved and rough . Botryoidal and stalactitic masses are more common, or again the mineral may be compact and granular or loose and earthy . As in the other rhombohedral carbonates, the crystals possess perfect cleavages parallel to the faces of the rhombohedron . The hardness is 5; specific gravity, 4.4 . The colour of the pure mineral is white; more often it is brownish, sometimes green or blue: a bright-yellow variety containing cadmium has been found in Arkansas, and is known locally as " turkey-fat ore." The pure material contains 52% of zinc, but this is often partly replaced isomorphously by small amounts of iron and manganese, traces of calcium and magnesium, and sometimes by copper or cadmium . Calamine is found in beds and veins in limestone rocks, and is often associated with galena and blende . It is a product of alteration of blende, having been formed from this by the action of carbonated waters; or in many cases the zinc sulphide may have been first oxidized to sulphate, which in solution acted on the surrounding limestone, producing zinc carbonate . The latter mode of origin is suggested by the frequent occurrence of calamine pseudomorphous after calcite, that is, having the form of calcite crystals . Deposits of calamine have been extensively mined in the limestones of the Mendip Hills, in Derbyshire, and at Alston Moor in Cumberland . It also occurs in large amount in the province of Santander in Spain, in Missouri, and at several other places where zinc ores are mined .

The best crystals of the mineral were found many years ago at Chessy near

Lyons; these are rhombohedra of a fine apple-green colour . A translucent botryoidal calamine banded with blue and green is found at Laurion in Greece, and has sometimes been cut and polished for small ornaments such as brooches . The name calamine (German, Galmei), from lapis calaminaris, a Latin corruption of cadmia (Kabala), the old name for zinc ores in general (G . Agricola in 1546 derived it from the Latin calamus, a reed), was early used indiscriminately for the carbonate and the hydrous silicate of zinc, and even now both species are included by miners under tie same term . The two minerals often closely resemble each other in appearance, and can usually only be distinguished by chemical analysis; they were first so distinguished by James Smithson in 1803 . F . S . Beudant in 1832 restricted the name calamine to the hydrous silicate and proposed the name " smithsonite " for the carbonate, and these meanings of the terms are now adopted by Dana and many other mineralogists . Unfortunately, however, in England (following Brooke and Miller, 1852) these designations have been reversed, calamine being used for the carbonate and smithsonite for the silicate . This unfortunate confusion is somewhat lessened by the use of the terms zinc-spar and hemimorphite (q.v.) for the carbonate and silicate respectively . (L . J .

S.) 966 fine high

altar of the 17th century; its lofty tower serves as a landmark for sailors . A gateway flanked by turrets (14th century) is a relic of the H6tel de Guise, built as a gild hall for the English woolstaplers, and given to the duke of Guise as a reward for the recapture of Calais . The modern town-hall and a church of the 19th century are the chief buildings of the quarter of St Pierre . Calais has a board of trade-arbitrators, a tribunal and a chamber of commerce, a commercial and industrial school, and a communal college . The harbour is entered from the roads by way of a channel leading to the outer harbour which communicates with a floating basin 22 acres in extent, on the east, and with the older and less commodious portion of the harbour to the north and west of the old town . The harbour is connected by canals with the river Aa and the navigable waterways of the department . Calais is the principal port for the continental passenger traffic with England carried on by the South-Eastern & Chatham and the Northern of France railways . The average number of passengers between Dover and Calais for the years 1902–1906 inclusive was 315,012 . Trade is chiefly with the United Kingdom . The principal exports are wines, especially champagne, spirits, hay, straw, wool, potatoes, woven goods, fruit, glass-ware, lace and metal-ware . Imports include cotton and silk goods, coal, iron and steel, petroleum, timber, raw wool, cotton yarn and cork . During the five years 1901–1905 the average annual value of exports was £8,388,000 (£6,363,000 in the years 1896-1900), of imports £4,145,000 (£3,759,000 in 1896–1900) .

In 1905, exclusive of passenger and

mail boats, there entered the port 848 vessels of 312,477 tons and cleared 857 of 305,284 tons, these being engaged in the general carrying trade of the port . The main industry of Calais is the manufacture of tulle and lace, for which it is the chief centre in France . Brewing, saw-milling, boat-building, and the manufacture of biscuits, soap and submarine cables are also carried on . Deep-sea and coast fishing for cod, herring and mackerel employ over r000 of the inhabitants . Calais was a petty fishing-village, with a natural harbour at the mouth of a stream, till the end of the loth century . It was first improved by Baldwin IV., count of Flanders, in 997, and afterwards, in 1224, was regularly fortified by Philip Hurepel, count of Boulogne . It was besieged in 1346, after the battle of Crecy, by Edward III. and held out resolutely by the bravery of Jean de Vienne, its governor, till after nearly a year's siege famine forced it to surrender . Its inhabitants were saved from massacre by the devotion of Eustache de St Pierre and six of the chief citizens, who were themselves spared at the prayer of Queen Philippa . The city remained in the hands of the English till 1558 , when it was taken by Francis, duke of Guise, at the head of 30,000 men from the ill-provided English garrison, only 800 strong, after a siege of seven days . From this time the Calaisis or territory of Calais was known as the Pays Reconquis . It was held by the Spaniards from 1595 to 1598, but was restored to France by the treaty of Vervins .