37 8 CLAY GENUS. It is found alfo in veins, and generally forms the bafis of amygdaloid. It frequently contains imbedded cryftals of mica and bafaltic hornblende, but does not, like bafalt, in clude augite or olivine. Geographic Situation. In Saxony, it is found at Scheibenberg, Annaberg, Wiefenthal, Joachimfthal, and Schlackenwalde: in Bohemia, at Bilin; and at Kinnekulle, and Nor- berg in Weftmannland in Sweden. Obfewations. t. It is confidered by Werner as intermediate be tween bafalt and clay. When bafalt contains mica> it is palling to wacce, becaufe mica is nearly charac* teriftic of wacce. 2. Near Joachimfthal, there is an immenfe rent filled with wacce, in which whole trees are found imbedded. 3. Many of the fofiils defcribed by Karften, Char- pentier, Reufs, Ferber, and other mineralogist where fuch appearances are to be obferved. I enjoyed the jnvaluable opportunity ef examining thefe places along w ' £ ^ Dr Mitchell, but we found in every inftance that difintegra tcC ^ greenllone had been confounded with wacce. arc
