gems, Ceylon, Sri Lanka, zircon, jargon, chemical analysis

Forbes chemically examines a nearly colorless crystal of “oriental jargon” from Ceylon to determine its composition and its relationship to zirconia-bearing minerals. After fusion with sodium carbonate and separation of silica, he isolates the principal earth and compares its chemical behavior with zirconia from Ceylon hyacinth. His analysis gives approximately 33.61% silica, 46.12% zirconia, 7.64% of an additional earth provisionally identified as “jargonia,” 12.32% sesquioxide of iron, and 0.24% loss. These proportions differ markedly from the theoretical composition of zircon (ZrO₂SiO₂), principally because of the substantial iron and supposed additional earth. Forbes notes that the material’s spectrum lacks the characteristic “jargonium” bands previously described by Sorby, although Sorby suggests this may be because the zirconia is present as an oxide or zirconia compound. Forbes concludes that the composition and chemical behavior of jargon require further investigation, particularly in light of contemporary uncertainty concerning zirconia and the proposed new earths associated with zircon minerals.