With the aid of the sleeve fracturing technique, rock deformability and rock stresses can be determined in only one borehole test. Axial borehole fractures are induced without fluid interaction with existing fractures and joints. Sleeve fracturing of blocks is described. Stress determination by means of sleeve fracturing in lava flow of the South Table Mountain, Colorado Test Site, are found to be of the same magnitude and directions as stresses determined by hydrofracturing and overcoring techniques