McCurry used an electron microprobe to analyze the volatile in glass inclusion of feldspar. McCurry concluded that Millennium eruption may have released 2000 Mt Cl. Liu used chromatography to analyze the average of volatile of 5 whole-rock samples, and the contents of halogen is 0.08%-0.11%. A more recent and more detailed study by Horn and Schmincke (2000) used an ion probe to analyze the average of volatile in 6 of matrix glass and 19 melt inclusions, and the average of content of Cl in melt inclusions and matrix glass were found to be 0.4762% and 0.3853%, respectively. Horn and Schmincke concluded that the Millennium eruption may have released 45 ± 10 Mt of Cl. Another author, Guo, who studies petrology and geochemistry, shows the average of contents of Cl in melt inclusions and matrix glass to be 0.45% and 0.33%, respectively. They concluded that Millennium eruption may have released 109.88 Mt of Cl, and 15.82 into the stratosphere. The Cl contents in the melt inclusions are similar to those of Mayor Island, and higher than those of Tambora (0.211%), Krakatau (0.238%) and Pinatubo (0.88-0.106%). The large difference of results between Guo and Horn is because Guo used higher volume and density of magma.