High temperature resistant vitreous inorganic fiber

A low shrinkage, high temperature resistant vitreous inorganic fiber having a use temperature up to at least 1330 °C, which maintains mechanical integrity after exposure to the use temperature and which is non-durable in physiological fluids, is prepared by the method of forming a melt with ingredients including greater than 71.25 weight percent silica, 0 to about 20 weight percent magnesia, and about 5 to about 28.55 weight percent of calcia, 0 to about 5 weight percent zirconia, and optionally a viscosity modifier in an amount effective to render the product fiberizable and producing fibers from the melt.