Burned flint

Thermoluminescence Amount of light emitted at high temperature Pottery, burned flint Textbox 24... 

When it consists of only silica and water, flint is basically colorless. Impurities within the stone, however, render colored varieties. Thus, much flint is tan, beige, or jet black with a brown homy appearance (the latter color is caused mainly by iron impurities), but there are also gray, pink, and even red varieties. If dark flint is heated to temperatures above 450°C, the outer layer changes to white. Flint that underwent such a heating process is known as burned or calcinated flint, a misnomer probably used because the white surface appears to have changed into lime (Luedtke 1992 Sieveking and Bart 1986). Burned flint is easier to work than is the natural mineral, a property... 

Seeds of fruits and small pieces of wood were found throughout the excavated area and a small proportion, about 5%, had been burned. SEM observations documented the species and burning of these specimens. Several types of wood were burned there, including willow, poplar, ash, and wild olive. The excavators of the site make a convincing argument that the clustered distribution of the burned flint and the presence of burned wood and seeds argue for the presence of several fireplaces at Gesher Benot Ya Aqov. 

Fig. 6.2 A raised isobar map of one of the occupation layers at Gesher Benot Ya Aqov. (a) Shows the distribution of aU flint in the layer (b) shows the distribution of burned flint in the layer. The differential distribution of the burned flint in smaU concentrations argues for the presence of fireplaces at the site...

Thermoluminescence (TL) dating Technique for absolute dating based on the principle of the rate of accumulation of TL after heating, used with burned flint and clay. 

Fireclays can be dividea into plastic clays and hard flint clays they may also be classified as to alumina content. Firebricks are usually made of a blended mixture of flint clays and plastic clays which is formed, after mixing with water, to the requirea shape. Some or all of the flint clay may be replaced by highly burned or calcined clay, called... 

Wick igniter utilized the heat produced by a slowly burning special wick, which was ignited by flint-steel, as above... 

Lime.—This substance, which forms an important constituent in flint-glass, maybe introduced either as a carbonate, or slaked or burned. Limestone, however, that contains proto-carbonate of iron, must be excluded from tha mixture for making white glass. The action of lima is to render the alkaline silicates insoluble, and when rightly balanced by the other ingredients, it promotes the fusion of the whole, and improves the quality, but when added in excess, the glass becomes hard and difficult to work, and subjoet to devitrification. 

Tho crude materials used in England in the manufacture of fine earthenware, are Cornish stone and China clay, a kind of kaolin brought from Cornwall, two varieties of plastic clay, both of which burn white, and chalk-flints. That class called ironstone china is made from ft mixture of plastic clay, kaolin, Comish stone in excess, and silica, Hie formula of which is subjoined —... 

FIGURE 16 Stagnant flint height representation for condensed phase burning. 

The burning shrinkage in the case of flint clays cannot be entirely attributed to the contraction accompanying vitrification. Considering the purity of these clays it is evident that part of the shrinkage is independent of this factor and must be due to a molecular change of another kind, that peculiar to many typical amorphous... 

Regardless of the practices adopted, slaking of most quicklimes results in the formation of grit. This may arise from uncalcined particles of limestone, from discrete impurities (e.g. flint), from water-burning of reactive lime and from drowning of low reactivity lime. 

High burned super- 51-55 SiOi 41-45 AbOi 3.175-3,200 2,600-2.800 155 2.65-2.75 130-145 Flint fireclay... 

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