touchstone

touch·stone

noun \ˈtəch-ˌstōn\

Definition of TOUCHSTONE

1

: a black siliceous stone related to flint and formerly used to test the purity of gold and silver by the streak left on the stone when rubbed by the metal

2

: a test or criterion for determining the quality or genuineness of a thing

3

: a fundamental or quintessential part or feature : basis <a touchstone film of that decade> <now considered a touchstone of the city's life — Michael Specter>

Examples of TOUCHSTONE

1. Good service is one touchstone of a first-class restaurant.
2. <his book has long been a touchstone for travel writing that aspires to be literature>

First Known Use of TOUCHSTONE

1530

Related to TOUCHSTONE

Synonyms

bar, barometer, benchmark, criterion, gold standard, grade, mark, measure, metric, par, standard, yardstick

Related Words

case, example, instance; average, norm, rule; acme, apex, meridian, peak, pinnacle, summit, zenith

Near Antonyms

aberration, abnormality, deviation

See Synonym Discussion at standard

Other Mining and Drilling Terms

ore, trepan, wildcat

Rhymes with TOUCHSTONE

agon, aitchbone, alone, atone, backbone, Bastogne, bemoan, Big Stone, birthstone, Blackstone, bloodstone, bluestone, bondstone, Boulogne, breastbone, bridge loan, brimstone, brownstone, call loan, calzone, Capone, capstone, cell phone, cheekbone, chinbone, cogon, cologne, Cologne, colon, colón, Colón, condone, copestone, corn pone, curbstone, cyclone, daimon, dapsone, debone, depone, dethrone, dial tone, disown, Dordogne, downzone, dripstone, drop zone, drystone, earphone, earth tone, end zone, enthrone, estrone, fieldstone, firestone, Firestone, flagstone, flowstone, flyblown, footstone, freestone, free zone, full-blown, gallstone, gemstone, Gijón, goldstone, gravestone, greenstone, grindstone, hailstone, halftone, handblown, hard stone, headphone, headstone, hearthstone, high-flown, hip bone, homegrown, hormone, hornstone, impone, ingrown, inkstone, in stone, intone, jawbone, jewel tone, keystone, León, leone, life zone, limestone, lodestone, long bone, Maidstone, milestone, millstone, moonstone, mudstone, nose cone, oilstone, orgone, ozone, pay phone, peptone, pinbone, pinecone, piñon, pipestone, postpone, potstone, propone, redbone, red zone, rhinestone, sandstone, shade-grown, shinbone, siltstone, snow cone, soapstone, splint bone, strike zone, T-bone, tailbone, thighbone, time zone, toadstone, tombstone, touch-tone, tritone, trombone, turnstone, twelve-tone, two-tone, Tyrone, unknown, unthrone, war zone, well-known, whalebone, wheel-thrown, whetstone, windblown, wishbone, Yangon

touchstone

noun    (Concise Encyclopedia)

Black, silica-containing stone used in assaying to determine the purity of gold and silver. The metal to be assayed is rubbed on the touchstone, and then a sample of metal of known purity is rubbed on the stone right next to it. The streaks of metal on the stone are treated with nitric acid, which dissolves impurities, thus increasing the contrast between the two samples when compared. Because other metals, such as copper, can be alloyed to silver without changing its colour significantly, the touchstone method is not usually used now to assay silver, though it is still used to assay gold and provides a reasonably accurate guide to quality.