A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

J

Jackhammer       Term for rock-breaking pneumatic hammer or rock drill.

Jackleg       A percussion drill used for drifting or stopping that is mounted on a telescopic leg which has an extension of about 2.5 m. The leg and machine are hinged so that the drill need not be in the same direction as the leg.

Jaw crusher       A machine in which rock is broken by the action of steel plates.

Jet       Device for spraying water, also the water spray itself.

Jig       A piece of milling equipment used to concentrate ore on a screen submerged in water, either by the reciprocating motion of the screen or by the pulsation of water through it.

Joint       A divisional plane or surface that divides a rock and along which there has been no visible movement parallel to the plane or surface.