The emission of electrons, photons, and positive ions was monitored during three-point bending, compression, and fast compression (impact loading) of single-crystal pentaerythritol tetranitrate (PETN). The emission appears to be fracture mode dependent with negligible emission from cleavage-type fracture and very intense electron emission accompanying impact. Possible causes of this enhanced emission are discussed in terms of shear effects and frictional grinding of the crystal fragments. Evidence of a microdischarge (electrical breakdown between fracture surfaces) during impact loading of the crystals is presented.