Min. [ad. Ger. felsstein, f. fels rock + stein stone. By early German mineralogists used vaguely for amorphous rocks; association with FELSITE has given it a more restricted meaning.] (See quot. 1865.)
1858. Geikie, Hist. Boulder, xii. 240. There are other traps, however, consisting entirely, or nearly so, of felspar, whence they are known as felstones.
1865. D. Page, Handbk. Geol. Terms (ed. 2), Felstone, the term now generally employed by geologists to designate compact felspar which occurs in amorphous rock-masses…. The term Felsile was at one time employed for the same purpose, but is now all but obsolete.
1875. Croll, Climate and Time, xxvii. 440. The top of the hill is composed of a compact porphyritic felstone, which is very much broken up.
attrib. 1882. J. Hardy, in Proc. Berw. Nat. Club, IX. 466. A very perfect felstone celt.
