Tenacity

Tenacity describes how a mineral responds to mechanical stress. Jade (nephrite) is one of the toughest gemstones because its fibrous, interlocking crystal structure absorbs impact, even though it only reaches Mohs 6.5. Diamond, the hardest natural substance, is actually brittle — it will shatter with a sharp blow. Tenacity is described using terms like brittle (diamond, topaz), tough (jade, jadeite), sectile (able to be cut with a knife, as in talc), and malleable (can be hammered into sheets).