Abstract: High-purity quartz sand serves as a critical material in various strategic emerging industries, such as semiconductors and photovoltaics. The quality of quartz sand is crucial for the application of products like single crystal silicon crucibles and quartz tubes. Besides impurity elements, gas-liquid inclusions are a significant factor affecting quartz quality. However, current detection methods for gas-liquid inclusions are mainly qualitative, lacking efficient and precise quantitative analysis techniques. This paper innovatively proposes the Double Extreme Case Analysis (DECA) method to quantitatively assess the content of gas-liquid inclusions. The process involves the quartz sand slices treated with the reagent were put under the microscope for observation and photographing, obtaining at least 300 images of quartz particles where the quartz appears transparent and the inclusions appear black. By statistically analyzing the images, the ratio of transparent (T) to non-transparent (NT) particles is calculated to evaluate quartz quality. The study of different quartz sands using DECA and crucible testing shows that quartz with a higher T ratio and lower NT ratio produces crucibles with excellent transparency, while quartz with a lower T ratio and higher NT ratio results in poor transparency. This method effectively addresses the challenge of quantitative gas-liquid inclusion detection and provides a reliable basis for evaluating high-purity quartz sand quality.