Abstract: We disclose glass compositions having an index of refraction of about 1.550 in the fiber form. Textile glass fibers formed from these glass compositions are especially useful for the reinforcement of clear plastics.This invention relates to fiberizable glass compositions. More specifically, this invention relates to textile glass fibers.We often use textile glass fibers for the reinforcement of plastics. Commercially available textile glass fibers for this purpose are E-glass and S-glass filaments. Recently, we developed a fiberizable glass composition in which we eliminated the potential pollutants boron and fluorine. The fibers formed from this glass composition compare favorably with E-glass in color, liquidus temperature, and viscosity.The index of refraction (1.576) of this glass composition, however, is too high for the reinforcement of clear plastics. That index should be about 1.550.We now have developed glass compositions which have an index of refraction of about 1.550 in the fiber form.