<p>Silica powder was obtained from the mud volcano of Napan Village following the co-precipitation method. This research aimed to determine the phase changes that occur in calcined silica with various temperatures. This research was carried out in three stages, there are the preparation of a mud volcano using the pre-treatment method, extraction of silica with sodium hydroxy solution, and calcination of silica with temperature variations. By analysis of XRF and XRD results, the mud volcano samples showed a high percentage of SiO₂ minerals. The results of silica characterization using XRD showed that uncalcined and calcined silica at 600^oC had an amorphous structure with broading peaks. Tridymite and cristobalite phases were detected in calcined silica at 800^oC and 1000^oC. Calcined silica at a temperature of 1000^oC transformed the tridymite phase to cristobalite with a decrease in the intensity of the tridymite phase while the cristobalite phase increased.</p>