Abstract
It is demonstrated that the technique of borehole notching is effective in ornamental rock quarrying, allowing a significant increase of the borehole spacing or smaller effective borehole pressures for a given spacing, so that the explosive loads and also the risk of damage to the rock can be reduced. The drilling of notches must be performed carefully and efficiently for those to be effective; for this a design of a notching machine prototype with two or four hammers is proposed.