gems, Ceylon, Sri Lanka.12, Ratnapura, Adam's Peak, Sabaragamuwa, amethyst, quartz, beryl, chrysoberyl, cinnamon stone, hessonite, chryoberyl, euclase, garnet, tourmaline, hyalite, kyanite, pleonaste, rock crystal, rose quartz, ruby, sapphire, sphene, spinel, topaz, zircon, feldspar, fluorite, epidote, tremolite, mica

Dr. Rudolph Gygax was a Swiss mineralogist employed by the British colonial government in 1847 to survey Ceylon's mineral resources. This 1847 publication outlines an early systematic survey of the geological formations and mineral resources of Sri Lanka (Ceylon), detailing crystalline rocks, corundum deposits, and plumbago. According to Sir James Emerson Tennent's 1859 account,