240 CLAY GENUS. Occurs moft commonly maflive, alfo finely diffemi- nated in chalcedony, and mofs-like in agate. The ftriped variety is fometimes imbedded in quartz. Internally its luflre is fhining, which approaches gliftening, and is intermediate between vitreous and refinous. . t . Fra&ure more or lefs perfe&Iy conchoidal, paffing into even and fine earthy. Fragments* indeterminately angular, more or lefs fharp edged. ■ Ufually opaque, feldom tranflucent on the edgeSj and that only when it approaches to jafper agate. Pretty hard, but in a higher degree than the fol lowing kind. Brittle Eafily frangible. Not particularly heavy. i b. Earthy common Jafper. Its colours are blood red and brownifh red; latter pafles into brown. Occurs-maflive and in rolled pieces. Fracture earthy. Fragments indeterminately angular, not particularly fharp edged. ; Opaque. Pretty hard, but in an inferior degree, Pretty eafily frangible. Not particularly heavy. GeognosM
