The Whetstone Quarry

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So the stones were important and, according to my source at the university, about 600 million years old. They were probably formed from fine volcanic ash that settled in this spot when it was an archipelago in a primordial sea, as Indonesia is today. Heat and pressure slowly compressed the volcanic debris into the beds of "slate" that now cap this ridge in the woods.

BEGINNINGS

It wasn't long after we began to use rocks for tools that we noticed their abrasive qualities and put them to use for polishing first other stones and then the newfangled tools of bronze and iron.

A wide variety of natural materials have been used to grind and polish metal. The natural stones are usually known by the name of their source. Beyond the familiar Arkansas stone, there are the Turkey stone, the Belgian, the Labrador, the Naxian, the Tam O'Shanter, the Washita, the Charnley Forest, and the Water of Ayr, among countless others. The Arkansas and the Washita are among those known to mineralogists today as novaculites, from the Latin word novacula, meaning "a razor." Another good word is the Celtic name for whetstone, passernix.

Other materials have been used as well. Britons once sharpened their scythes on wooden "ripe sticks" covered with tallow and sand. Armorers polished metal with handfuls of "scouring rushes" or "horse tails," a plant which isolates silica in its cells. For stropping, leather, often charged with jewelers rouge (available at hardware stores as buffing compound), is the most commonly used material. I have occasionally used the undersides of woody shelf fungi that grow out of the sides of trees for this purpose.

The makers of artificial stones try to capture some of the romance of natural materials by giving them such names as the "India," but they are made of bonded synthetic abrasives such as silicon carbide. In his Dictionary of Tools, R.A. Salaman relates the story of a Brixton ironmonger who, when he could not convince carpenters of the value of the new artificial oilstones (this was in 1901), would throw one against the wall. As the stone would not break, he sometimes made the sale. These artificial stones have largely replaced the natural ones in today's market, except for the finest work.

The favored natural abrasive was, and is, about the most common material on earth: silicon dioxide, or silica-sand. Indeed, the root of the word sand goes back to the ancient Greek psen, meaning "to rub." Silica is hard and sharp when the grains are fresh. When rubbed about, though, the sharp edges become rounded and will no longer cut as well. Beach sand, which has been knocked about a lot, will not work as well as grit that is freshly eroded from the rock. In his report on McCauley's whetstones, Olmstead mentioned that one of their desirable qualities was that they "wear away fast." Using such a stone constantly reveals fresh surfaces of sharp particles. A stone that does not wear away faster than the metal that it is abrading will quickly glaze and stop cutting, either from the sharp edges having been rounded or from the particles of metal filling the spaces between the abrasive grains.

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