" At least eighty percent of the world's production of this mineral comes from South Australia, although the "Mexican  ► fire" variety of this mineral is mined in the state of Queretaro.
This substance replaced mineralized bone in the Addyman plesiosaur specimen and in the thighbone of a brachiosaur discovered underneath Lightning Ridge. Miners of this substance live in underground homes called "dugouts" at the field beneath the Stuart Range at the town of (*) Coober Pedy, whose name is supposedly an Aboriginal word for "white man's hole in the ground." At least eighty percent of the world's production of this mineral comes from South Australia, although the "Mexican  ► fire" variety of this mineral is mined in the state of Queretaro. For 10 points, name this amorphous form of silica, the traditional birthstone for the month of October.
This substance replaced mineralized bone in the Addyman plesiosaur specimen and in the thighbone of a brachiosaur discovered underneath Lightning Ridge.
opals