[en] Image-tube scanner measurements of Preston's (1959) metal abundance indicator have been made for 47 RR Lyraes. Another index that is a measure of metallic-line absorption in the region of the G-band has also been determined. From curve-of-growth analyses of 13 field RR Lyraes, the relationship [Fe/H] = -0.16 ΔS(K)-0.23 is found, where [Fe/H) = log (Fe/H)/sub */-log (Fe/H). The problem of the anomalous horizontal-branch distribution functions in M13 and NGC 7006 is discussed in the light of these new observations. It is suggested that differences in the location of the horizontal branch in clusters with the same [Fe/H] result from different degrees of mixing between the envelope and the hydrogen-burning shell in the horizontal branch progenitor. (U.S.)