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Jurassic period

A geological period 208-146 million years ago. Dinosaurs and early birds inhabited this period

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Jet drilling

The use of a high-temperature flame to fuse a rock target, and a stream of water to induce decrepitation and fragmentation, and to flush the fragment out of the target. This technique is progressively used to “drill” a desired length.

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Jaw crusher

A machine in which pulverizes ore fed between 2 oscillating steel plates.

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Jade, Jadeite

A hard, monoclinic mineral, 4[NaAlSi2O6] of the pyroxene group, commonly used in jewelry

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Jackhammer

A handheld, automatically rotated percussive rock drill usually powered by compressed air