Abstract: Through making technical improvements on the photograph taken with cathodeluminescence and measuring procedures,the author accomplishedthe observation and photograph with polarization and cathodeluminecence while the rapid quantitative analysis of isotopic chemical composition have been made by an electron probing analyzee on the secondary enlarged fringes of quartz. Results show that Al₂O₃ content would obviously vary with secondary enlarged fringes of quartz developed at different stages of diagenesis. With the basis mentioned above, the secondary enlargement of quartz is quantitatively defined by corresponding grades. Finally, the formative conditions of the secondary enlarged fringes of quartz are studied in details.