The change of colour which occurs when chemicals are put under stress in the solid state by mechanical grinding, crushing and milling; by friction and rubbing; or in the solid or solution state by high pressure or sonification is covered by the generic term mechanochromism. Specifically colour change under pressure is known as piezochromism and under grinding or attrition tribochromism.
1. Bamfield, Peter and Hutchings, Michael G, Chromic Phenomena: the technological applications of colour chemistry, Royal Society of Chemistry, Cambridge UK, pages 104-5, 2010. ISBN:978-1-84755-868-8.
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