Kaolin, fire-clays and brick-clays are common to all the states.
The term clay is often used by chemists to denote hydrated silicate of alumina (Al 2 O 3 2SiO 2.2H 2 O), of which kaolin or china clay is a fairly pure form.
Amakusa produces a little coal and fine kaolin, which was largely used in former times by the potters of Hirado and Satsuma.
Coal has been worked near Noumea, and kaolin is found in places.
Minerals produced in small quantities include gypsum, millstones, salt and sandstone, and among those found but not produced (in 1902) in commercial quantities may be mentioned allanite, alum, arsenic, bismuth, carbonite, felspar, kaolin, marble, plumbago, quartz, serpentine and tin.
Lignite and coal, some graphite and kaolin, are mined, as also amber, which is often found in big lumps.
The environs of Creil (Oise) and Chteau-Landon (Seine-et-Marne) are noted for their freestone (pierre de taille), which is also abundant at Euville and Lrouville in Meuse; the production of plaster is particularly important in the environs of Paris, of kaolin of fine quality at Yrieix (1-Jaute-Vienne), of hydraulic lime in Ardche (Le Teil), of lime phosphates in the department of Somme, of marble in the departments of HauteGaronne (St Beat), Hautes-Pyrnes (Campan, Sarrancolin), Isre and Pas-de-Calais, and of cement in Pas-de-Calais (vicinity of Boulogne) and Isre (Grenoble).
Kaolin, or porcelain clay, although capable of application to commercial purposes, has not as yet been utilized to any extent, although found in several places in New South Wales and in Western Australia.
Near Tokat copper pyrites, with iron and manganese, kaolin and coal are found; but most of the copper worked here comes from the mines of Keban Maden and Arghana Maden, on the upper Euphrates and Tigris.
Florida is also the principal source in the United States for fuller's earth, a deposit of which, near Quincy, was first discovered in 1893 and clay (including kaolin) is also mined to some extent.
The raw materials used in the manufacture are: (I) iron-free kaolin, or some other kind of pure clay, which should contain its silica and alumina as nearly as possible in the proportion of 2SiO 2: Al203 demanded by the formula assigned to ideal kaolin (a deficit of silica, however, it appears can be made up for by addition of the calculated weight of finely divided silica); (2) anhydrous sulphate of soda; (3) anhydrous carbonate of soda; (4) sulphur (in the state of powder); and (5) powdered charcoal or relatively ash-free coal, or colophony in lumps.
Kaolin is found in the state; in 1907 the total value of all clay products was $928,579.
The existence of porcelain clay in Hizen was not discovered for many years, and Shonzuis pieces being made entirely with kaolin imported from China, their manufacture ceased after his death, though knowledge of the processes learned by him survived and was used in the production of greatly inferior wares.
The third clearly differentiated epoch was inaugurated by the discovery of true kaolin at Izumi-yama in Hizen, the discoverer being one of the Korean potters who came to Japan in the train of Hideyoshis generals returning from the invasion of Korea, and the date of the discovery being about 1605.
Those of economic value are kaolin, mined chiefly in the vicinity of Hockessin, New Castle county, the static kaolin product being exceeded in 1903 only by that of Pennsylvania among the states of the United States; granite, used for road-making and rough construction work, found near Wilmington; and brick and tile clays; but the value of their total product in 1902 was less than $500,000.
Potters' clay, kaolin and felspar, which have largely facilitated the development of the flourishing porcelain industry, are found in various parts of the country, which is also fortunate in possessing sand suitable for use in the manufacture of the glass for which Bohemia has long been famous.
Kaolin or China clay is essentially a pure disilicate (Al 2 O 3.2SiO 2.2H 2 O), occurring in large beds almost throughout the world, and containing in its anhydrous state 2 4.4% of the metal, which, however, in common clays is more or less replaced by calcium, magnesium, and the alkalis, the proportion of silica sometimes reaching 70%.
Aluminium sulphate, known commercially as "concentrated alum" or "sulphate of alumina," is manufactured from kaolin or china clay, which, after roasting (in order to oxidize any iron present), is heated with sulphuric acid, the clear solution run off, and evaporated.
Tin ore of excellent quality is found in the province of Bauchi, alkali salts are abundant in Kano province, iron ore and red and yellow ochres are found in Kontagora and other provinces, kaolin (china clay) and limestone in the west central regions.
In the vicinity are large beds of kaolin, 30 m.
Much of the raw material for this industry, such as ball, flint, and spar clays and kaolin, is imported from other states.
Steamers ply regularly in two directions from St Petersburg - to the monasteries of Konnevitz and Valamo, and to the mouth of the Svir, whence they go up that river to Lake Onega and Petrozavodsk; and small vessels transport timber, firewood, planks, iron, kaolin, granite, marble, fish, hay and various small wares from the northern shore to Schlusselburg, and thence to St Petersburg.
Kaolin may with advantage be used in addition to or in part substitution for sand, because the double silicate thus formed is more fusible than the single silicate of lime.
Various mineral paint bases (apart from lead, zinc, baryta and kaolin) are produced in small quantities.
There are abundant deposits of gypsum, alum, kaolin, marble and similar materials.
Among the less important Spanish minerals are manganese (chiefly in Ciudad Real), antimony, gold, cobalt, sodic sulphate, sulphate of barium (barytes), phosphorite (found in Chceres), alum, sulphur, kaolin, lignite, asphalt, besides a variety of building and ornamental stones.
The principal substances of this description are kaolin, muscovite and chlorite.
Kaolin and muscovite are formed principally after felspar (and the felspars are the commonest minerals of all crystalline rocks); also from nepheline, leucite, scapolite and a variety of other rock-forming minerals.
Some of these are recognizable as pale yellowish and white mica; others seem to be chlorite, the remainder is perhaps kaolin, but, owing to the minute size of the flakes, they yield very indistinct reactions to polarized light.
It is certain, however, that the finer-grained rocks are richest in alumina, and in combined water; hence the inference is clear that kaolin or some other hydrous aluminium silicate is the dominating constituent.
It is almost always more than would be the case if the rock consisted of kaolin mixed with muscovite.
Some clays, however, such as fireclays, contain very little potash or soda, while they are rich in alumina; and it is a fair inference that hydrated aluminous silicates, such as kaolin, are well represented in these rocks.
It consists of very fine scaly kaolin, larger, shining plates of white mica, grains of quartz and particles of semi-decomposed felspar, tourmaline, zircon and other minerals, which originally formed part of the granite.
The felspar decomposes into kaolin and quartz; its alkalis are for the most part set free and removed in solution, but are partly retained in the white mica which is constantly found in crude china-clays.
The kaolin may be washed away from its original site, and deposited in hollows or lakes to form beds of white clay, such as pipe-clay; in this case it is always more or less impure.
Materials for porcelain, including flint, feldspar and kaolin, abound in the east portion of the Piedmont, the kaolin chiefly in Cecil county, and material for mineral paint in Anne Arundel and Prince George's counties, as well as farther north-west.
This mature weathering, resulting in the relatively complete separation of the quartz from the kaolin, and both from the calcium carbonate and other basic materials, implies conditions of rock decay comparable to those of the present time.
The islands have large (unworked) supplies of pumice, sandstone, sulphur, gypsum, alum and mineral-paint ochres, and some salt, kaolin and sal-ammoniac, but otherwise they are without mineral wealth other than lava rocks for building purposes.
Kaolin abounds in Chester and Delaware counties, and fire-clay in several of the western counties.
Kaolin thus seems to be the best ore, and it would undoubtedly be used were it not for the fatal objection that no satisfactory process has yet been discovered for preparing pure alumina from any mineral silicate.
Considerable quantities of aluminium are obtained from the kaolin deposits in the vicinity.