How and where are Opals formed and found?

Opal is considered a mineraloid and has no crystal structure.  The term used for no structure is amorphous.  Opal is scientifically written as SiO2 NH2O. It is called hydrated silicon dioxide.  Opal is normal a stone that is mixed with water.  Stones that can commonly form Opal are limestone, basalt, rhyolite and sandstone.  While Opal contains water, the water content does vary by stone.  For instance, Opal has been found with water content approaching 20%, however, most Opal stones used for ornamental jewelry usually have water content of 3% to 10%.

Opal comes in many varieties of colors including white, blue, black, gray, red, yellow and brown.  There are two types of Opal, common and precious, common Opal has truly no structure, but precious Opal does have certain structural elements that makes it very attractive.

Opal usually is formed as a mineraloid gel that is created at very low temperatures.  This mineraloid gel is usually created at temperatures less than 200 degrees Celsius and can occur in fissures of many types of rock.

It has a distinct internal color composed of very tightly packed silica spheres.  Wonderful colors can come from these tightly packed spheres that can range in size from 150 to 300 nano meters in diameter.  Sometimes this phenomenon is called opalescence and it gives the Opal a wonderful play of color.

This gemstone is found all over the world; however the precious variety of Opal is usually mined in one specific spot in the world – Southern Australia.  Southern Australia is renown as the Opal capital of the world and is responsible for up to 95% of the Opal mined.

Different colors, shapes and sizes that Opal comes in

Opal is one of the more popular stones, mainly due to its wonderful variety of rich and beautiful colors.  If you are interested in purchasing ornamental jewelry and are interested in stones that give you a great choice of attractive colors, shapes and styles, Opal should be at the top of your list.

Opal is a precious stone that is made from silica and there are many stones that Opal can be.  Besides silica rock, Opal also includes water, with usually a water content of 3% to 10%. Opal is a cryptocrystalline, meaning it has extremely small crystal structures that are very fine and can’t be seen with the naked eye.  Other types of cryptocrystallines are Agate and Onyx.

Opal comes in a wonderful variety of colors including white, black, yellow, orange, brown and red.  Red is one of the more popular Opal colors.  There are usually two types of red colors –cherry red and fire red.  Fire red is usually the most popular and possibly the most expensive due to its wonderful hue.

Opals are mined in larger sizes, so they can easily be cut and sized to fit almost any type of rings.  Other types of jewelry that Opal works well with are bracelets, necklaces, brooches, earrings and you can even find figurines and statuettes made from precious Opal.

Opal is found in most regions of the world, however precious gemstone Opal is usually found in one place- Southern Australia.  More than 95% of the world’s precious Opal comes from Australia.