This invention is concerned with spontaneous opal glasses wherein sodium fluoride (NaF) and strontium fluoride (SrF.sub.2) constitute the predominant opacifying phases. More specifically, the opal glasses of the instant invention have compositions within the Na.sub.2 O--SrO--Al.sub.2 O.sub.3 --SiO.sub.2 --F field and exhibit a dense white appearance, a softening point above 755.degree. C., a strain point in excess of 500.degree. C., a coefficient of thermal expansion (0.degree.-300.degree. C.) in excess of 65.degree. .times. 10.sup.-7 /.degree. C., and satisfactory resistance to weathering and dishwasher environments.