the contact between the rock and the nut will vary according to the contours of the crack in fig1 a crack having similar flaring geometry is shown except nut 10 is wedged into the crack with the triangulation or contact points on face 16 and legs 40 and 42 fig1 illustrates that by manufacturing the nut with the two pairs of opposed concave and convex faces a nut that has a width dimension that is greater that its depth dimension allows the same nut to be used in cracks of different sizes an alternate embodiment of nut 10 is shown in fig1 nut 10 of fig1 has the same basic configuration as the nut shown in fig1 through 12 except that the curvature of convex front face 44 is asymmetric about a longitudinal centerline extending along the face the asymmetrically curved face provides for different placement options in cracks having different contours moreover convex side face 16 may likewise be formed with an asymmetric curvature and either one or both of the concave curves on faces 14 and 18 could be asymmetrically curved fig1 shows an ingot 46 of extruded metal from which a plurality of nuts 10 will be milled the alloy composition of ingot 46 is selected according to design preferences and strength requirements and is closely controlled to meet desired specifications the size dimensions of ingot 46 depend upon the size of the nuts that will.