Flint

Flint was widely used by early humans. The stone is relatively common and produces sharp edges when fractured, making it ideal for tools and weapons. The adzes (shown left and middle) were used for shaping wood and the sickle (shown right) was used in harvesting during the late Stone Age. Note: The wooden handles are reproductions. Encarta Encyclopedia Dorling Kindersley

Flint is a common variety of quartz, with a dull, usually dark color, often found as nodules in chalk deposits. Highest quality flint is from the coastal chalk deposits of Great Britain and northern France, and poorer grades occur in the Cretaceous limestones of the United States and various other parts of the world.

Flint is a hydrated silica that, under certain conditions, appears to lose water at its surface leaving a thin, porous coating, or patina, of white silica. On the new surfaces of freshly fractured fragments, the flint has a waxy luster.

Flint breaks with a conspicuous conchoidal fracture, producing sharp edges. Prehistoric peoples found fragments of flint useful for sharp weapons and cutting instruments such as axheads, arrowheads, and knives. When flint is struck with steel, sparks are readily produced; it was therefore extensively used in the past for igniting tinder and for firing gunpowder in flintlock arms.

Flint is principally used today as an ingredient of fine pottery. “Flints” used in cigarette lighters are an alloy of rare earth metals and iron and have no relation to the quartz flint.

Sometime after people began to use stone for tools, they found that by rubbing together pieces of flint they could produce sparks that would set fire to wood shavings. Scientists have found evidence that people used pieces of flint and iron to produce sparks for fires 25,000 to 35,000 years ago.

The cryptocrystalline varieties of quartz are often divided into two general classes, fibrous and granular. The fibrous varieties, which include agate, carnelian, heliotrope, onyx, and chrysoprase, are all forms of chalcedony. The granular varieties include chert, flint, jasper, and prase.

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