We have studied the effect of zirconia additions on the properties of basalt glasses and fibers. The solubility limit of ZrO2 in basalt glasses is determined to be 7.1 wt %. Fibers produced from modified basalt glass contain both tetragonal and monoclinic zirconia. The highest ZrO2 concentration in basalt fibers is 3.1 wt %. We have determined the fiber drawing temperature ranges and assessed the tensile strength and alkali resistance of the fibers. With increasing ZrO2 content, the tensile strength of the fibers (d = 11−12 μm) decreases from 1.8 to 0.6 GPa. The addition of less than 3.1 wt % ZrO2 increases the alkali resistance of the basalt fibers by 37%. The addition of more than 3.1 wt % ZrO2 to the glass batch reduces the alkali resistance and tensilestrength of the basalt fibers.