Ejigu *, Assamen Ayalew, Desalegn Gezahegn Ketemu, Sisay Awoke Endalew, and Wudu Yimer Assen. “Challenges in Utilization of Precious Opal in Ethiopia: A Case Study from the Delanta Area, South Wollo, Ethiopia”. Abyssinia Journal of Science and Technology 5, no. 2 (December 31, 2020): 14–21. Accessed October 1, 2022. https://journals.wu.edu.et/index.php/ajst/article/view/112.