In other words, the Fluorides of all the non-metals that can form Fluorides.
"Uller Uprising"
Henry Beam Piper, John D. Clark and John F. Carr
Of course, this won't be anything like basalt in composition-it'll be intensely compressed metallic Fluorides, with a very high metal-content.
"Uller Uprising"
Henry Beam Piper, John D. Clark and John F. Carr