344 CLAY-GENUS. Geognostic Situation.' it is found wherever the rocks already mentioned occur, which is in almolt every quarter of tire globe. U/e. It was formerly ufed inftead of glafs fo^ windows and lanterns,_ abu till very lately it was ufed m the Rufiiau navy, as its great eia!‘ic<ty rendered it lef* liaise than glals to break on the dilchaige of cannon- r lhe udc-t for this purpofe was dug in the neighbour' t hood ot likutfk and limena in oiberia. Obfervation, The blackifh green variety is the link.which con* needs it with chlorite flate. TWENTY"