No. When opals were first found in Australia, they were not thought to be opals because they were a milky white in appearance. Opals found elsewhere in the world were mostly black.
Opals are amorphous because they have no definitve shape. As an example, quartz has a specific crystal shape. Opals can be any shape.
Nobody MADE opals. They're mined out of the ground.
Opals cannot be used as foods. They are hard, precious stones.
Neither opals or any other gemstone will make you invisible.
Some opals are known as black opals, this is when they have a mainly black colour. In general a black opal is very dark blue and has flecks of other colours within
The volcano itself does not make the opal. The lava, be it Rhyolite or Basalt has air bubbles in it (called vesicles) these air pockets of many differing sizes are the future home of the opals. After time wheh the lava cools any silica rich springs begin a slow deposition of silica which, if the conditions a correct, will form common and precious opal. The volcano creates the matrix (or host rock) of the opal.
Three different types of Opal are found in Australia:Fire Opals are mined in South Australia near Coober Pedy.Black Opals are mined in New South Wales near Lightning Ridge.Boulder Opals are mined in the western Queensland.
No they do not shrink.
Opals in Queensland are mined at Yowah, just outside of Quilpie in the far west of the state.
Yes. Coober Pedy is still a major producer of opals.
Opal is a form of quartz, but in the form of tiny spheres. About 150 - 300 nm in diameter, and packed in such a way as to form a diffraction grating. Australia produces 97% of world production.