Lava. 387 cut does not belong to this fpecies, although it has been afferted by feveral mineralogies, but to the fl°etz trap rocks. Ob/ervation. Hauy, in his Treatife on Mineralogy, enumerates following fpecies of lava: i.lSafaltic lava. 2. et rofdiceous lava. 3. Felfpathic lava. 4. Atnphige* "° Us 5. Vitreous lava, comprehending obfi- Ian > pearlftone, and pumice. 6. Scoriaceous lava. Of all thefe the only true lava is the lalt mentioned; e others, as will be fhewn in the Geognofie, are Natural unaltered rocks. I THIRTIETH I \
