A study was conducted on the extraction of volcanic ash from Mount Sinabung through the coprecipitation method to recover silicon dioxide (SiO2). X-ray fluorescence (XRF) analysis showed that the SiO2 content in volcanic ash was 48.5%, and after extraction, it was 99.1%. The morphology showed by scanning electron microscope (SEM) indicated that SiO2 looks cleaner and tends to be the same size compared to the volcanic ash sample. The average particle size of volcanic ash and extracted SiO2 were 32.28571 ± 2.51259 and 12.97521 ± 0.60657 µm, respectively. The X-ray diffractometer (XRD) analysis showed that the crystal structure of the volcanic ash sample was quartz, maghemite, and cristobalite. Besides, the extracted SiO2 had an amorphous quartz crystal structure. The test using fourier transform infrared (FTIR) resulted in the absorption of 1095.57 cm-1 and 798.53 cm-1 for the Si‒O‒Si and Si‒OH groups which were groups of siloxanes and silanols, respectively.