Äiamanline Spar. 337 After tliefe we may perhaps place the heavy felfpar mentioned by Mr. Briffon, ealled in Rome Feräe di Corfica Duro; its coloUr is dead white, with large blotches of green, and its hardnefs cxtraordinary. Its fp. gr. 3,105. And another, mentioned by Mr. Mörveäu, found in Le Ferez, of great hardnefs, whofe fpecific gravity was 3,075 ; but, as it yielded'a Iittle to the heat of a furnace, it is probable it contained fome mixtur? of cortimon felfpar.