Latitude: 12° 39′ 38.952″ N
Longitude: 107° 46′ 56.316″ E
Administrative location: Tân Định village, Đắk Gằn ward, Đắk Mil district, Đắk Nông province.
Opal has been widely known and used for castle decoration and jewelry. Opal jewelry is valuable, even more expensive and scarce than diamonds and ruby. Opal is the symbol of the Libra star in Zodiac signs.
Opal-Chalcedon forms in the holes of many different types of rocks, especially in lava-derived rocks. A majority of Opal-Chalcedon is generated in relatively low temperature and is the deposit of SiO2-rich solution. Active volcanoes are the typical geographic activity in Daknong Geopark in the Pliocene IV age.