The touchstone allowed anyone to easily and quickly determine the purity of a metal sample. This, in turn, led to the widespread adoption of gold as a standard of exchange. Although mixing gold with less expensive materials was common in coinage, using a touchstone one could easily determine the quantity of gold in the coin, and thereby calculate its intrinsic worth.
Operationedit
Drawing a line with gold on a touchstone will leave a visible trace. Because different alloys of gold have different colors (see gold), the unknown sample can be compared to samples of known purity. This method has been used since ancient times. In modern times, additional tests can be done. The trace will react in different ways to specific concentrations of nitric acid or aqua regia, thereby identifying the quality of the gold: 24 karat gold is not affected but 14 karat gold will show chemical activity.
^"Touchstone". Oxford English Dictionary. Retrieved 10 March 2013.
^Venable, Shannon L. (2011). Gold: A Cultural Encyclopedia. Santa Barbara, CA: ABC-CLIO, LLC. p. 264. ISBN978-0313-384318.
^Bisht, R. S. (1982). "Excavations at Banawali: 1974–77". In Possehl, Gregory L. (ed.). Harappan Civilization: A Contemporary Perspective. New Delhi: Oxford and IBH Publishing Co. pp. 113–124.
This article about materials science is a stub. You can help Wikipedia by expanding it.
touchstone, assaying, tool, this, article, about, assaying, tool, metaphor, touchstone, metaphor, other, uses, touchstone, disambiguation, touchstone, small, tablet, dark, stone, such, slate, lydite, used, assaying, precious, metal, alloys, finely, grained, su. This article is about the assaying tool For the metaphor see Touchstone metaphor For other uses see Touchstone disambiguation A touchstone is a small tablet of dark stone such as slate or lydite used for assaying precious metal alloys It has a finely grained surface on which soft metals leave a visible trace 1 Touchstone set Contents 1 History 2 Operation 3 See also 4 ReferencesHistory editThe touchstone was used during the Harappa period of the Indus Valley civilization ca 2600 1900 BC for testing the purity of soft metals 2 It was also used in Ancient Greece 3 The touchstone allowed anyone to easily and quickly determine the purity of a metal sample This in turn led to the widespread adoption of gold as a standard of exchange Although mixing gold with less expensive materials was common in coinage using a touchstone one could easily determine the quantity of gold in the coin and thereby calculate its intrinsic worth Operation editDrawing a line with gold on a touchstone will leave a visible trace Because different alloys of gold have different colors see gold the unknown sample can be compared to samples of known purity This method has been used since ancient times In modern times additional tests can be done The trace will react in different ways to specific concentrations of nitric acid or aqua regia thereby identifying the quality of the gold 24 karat gold is not affected but 14 karat gold will show chemical activity See also editLitmus test Spot analysis Streak testReferences edit Touchstone Oxford English Dictionary Retrieved 10 March 2013 Venable Shannon L 2011 Gold A Cultural Encyclopedia Santa Barbara CA ABC CLIO LLC p 264 ISBN 978 0313 384318 Bisht R S 1982 Excavations at Banawali 1974 77 In Possehl Gregory L ed Harappan Civilization A Contemporary Perspective New Delhi Oxford and IBH Publishing Co pp 113 124 nbsp This article about materials science is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Touchstone assaying tool amp oldid 1195514815, wikipedia, wiki, book, books, library,
