Wacce. 279 8re ^ le true wacce of Werner, others, however, are ttioft evidently greenftone. Full illuftrations on this u bje<ft win be given in the Geognofie. 4 The gray wacce of Werner which is an aggre- § at e rock, compofed of fragments of flinty flate, clay and quartz, connefted by a bafis of clay ate , not be confounded with this fpecies. TWENTY