The change of colour which occurs when chemicals are put under stress in the solid state by mecahnical 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

Piezochromism

Piezochromism describes the tendency of certain materials to change color with the application of pressure. This effect is particularly pronounced in plastics.-External links:*...

 and under grinding or attrition tribochromism

Tribochromism

Tribochromism refers to a change in colour of a material caused by mechanical friction.Tribochromatic materials are used when friction has to be detected. These materials generally change colour under mechanical stress conditions and then the colour gradually fades once the stress is removed....

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Reference

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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