After bringing the dirt to the surface, it is initially processed by washing away all the ordinary dirt and leaving behind potential opal stones. This is usually done in an “agitator,” a modified stationary cement mixer. Water is pumped through while the dirt rotates inside. Sludge pours from the mesh-covered openings in the side of the agitator as the dirt is washed away. What remains are known as tailings. Noodling: Source : This is one of the most effective ways of finding opal, but also the most laborious. The length of the shaft can be as short as three meters or as long as twenty. That concludes part 4. In part 5 we learn about the types and characteristics of some of the major types of opal available today. Opal is a very delicate gemstone...