Brazilian Opals are mined in the northeast region of the state of Piaua. Many are found in a quarry at the foot of a sandstone cliff and are hand-dug.
There are no large-scale opal fields, and the only equipment used is a generator. Most opals are good fire Brazilian crystal opal.
Brazilian opals are known as semi translucent to white translucent and have less water composition than Australian opals.
Australian opals have on average less than 10% water composition but Brazilian opals on average have less than 5% water
Brazilian opals forms in veins or layers of opals color ,and in alluvial deposits that has been washed down by rivers over centuries, or mined on slopes between source and present river floors.
Australian opals forms as nobbies or in seams ,but Brazilian opal has been formed differently in that the dominant rock is sandstone and siltstones.,
Clay forms in these veins and opal is associated with clay and clay forms at the sandstone point with sandstone veins.
