A woman was at San Onofre State Beach collecting rocks with her children, when a fire erupted in her shorts causing 2nd and 3rd degree burns.
Initial tests indicate two of the rocks had phosphorus on them, Denise Fennessy, Orange County environmental health official, told The Associated Press.
Phosphorous can burn when exposed to air, Concepcion said. He said the rocks were 2 to 3 inches round. One had green specks and another had orange specks.