Opal Properties Facts and Photos
1. An Introduction to Opal
2. Myths and Healing Properties
3. More Facts
4. Article Photos
5. Our Collection of Common Opal
Introduction to Opal
Precious opal and common opal from a geological perspective are almost identical. The main difference is their appearance.
Precious opal boasts an iridescence known as 'play of colour'. These stones have been highly prized since Roman times.
Common opal is mostly opaque, can be found in many different colours but does not exhibit 'play of colour'.
The optical phenomenon seen in precious opal is caused by the reflection and scattering of light. It comes from minute uniformly sized closely packed silica spheres. These formed when groundwater rich in minerals seeped into deep cracks and voids within Earth's crust and subsequently dried up.
Around ninety five per cent of the world's opals come from the outback deserts of Australia. The remaining five per cent are mined in Mexico, Brazil and the U.S states of Idaho and Nevada.
More recently opals have been found in Ethiopia and Mali.
Opals were discovered by Australian gold prospectors in 1863. They are believed however to have been mined much earlier by the Aztecs in South and Central America.
Some reports state opals from Ethiopia were being used as tools as early as 4000 BC. Factual evidence to support this is fairly vague.
Legends Myths and Healing Properties
The origins of the name opal may have come from the Sanskrit word 'upala' meaning 'valuable stone'. Upala may have come from the Greek 'opallios' which loosely means 'a gem with a kind of play of colour'.
Legends and myths have been associated with rocks and minerals for thousands of years.
A story once told by Australian aborigines claim God came down to earth on a rainbow to bring the message of peace to all mankind. At the spot where his foot touched the ground opals came alive and sparkled with the colours of the rainbow.
The ancient Greeks believed opals could give the wearer the power of foresight. The Romans revered them as a symbol of hope and purity and believed they could offer protection from disease.
Eastern cultures regarded opal as a symbol of truth whilst ancient Arabs believed they came from heaven. They also believed they acquired the play of colour from flashes of lightning.
During the Middle Ages opals were thought to be beneficial for eyesight. Some claimed they they could render the wearer invisible. For this reason they were often carried by thieves.
The French Emperor Napoleon gave his wife Josephine a magnificent opal called 'The Burning of Troy'. The name came about because of the variation of colour.
Today opal is considered to be a stone of true love. It enhances positive characteristics for those born under the zodiac sign of cancer. It's the modern and ayurvedic birthstone for the month of October.
A delicate stone which enhances psychic and mystical visions, it stimulates originality and boosts creativity.
Opal is a stone of reflection, it picks up on positive feelings and memories and amplifies them.
Associated with love, passion and desire, opal can stabilise emotions and gives the confidence to explore intimate feelings. It encourages a positive attitude and brings loyalty, respect and understanding.
A Few More Facts
A superstition brought about by the novel Ann of Geierstein written in 1829 by Walter Scott damaged the stone's popularity. The book described opal as being unlucky. Its reputation was gradually restored by public figures including Queen Victoria and French actress Sarah Bernhardt.
Common opal is not as well known or as popular as the precious variety. It can be found in many different colours but is best known for being a pink or green stone. The reason it's called 'common' opal is because it can be found in many countries around the world.
When used for gemstones both precious and common opal are polished as cabochons.
Boulder opal forms in thin veins within ironstone boulders. The main constituents of these fine grained heavy and compact sedimentary rocks are oxides of iron, clay and/or sand.
Freshly broken ironstone is usually grey. The brown external appearance is due to the oxidation of the stone's surface. Ironstone can also be found in a red and black banded form. When polished as a gemstone this material is also known as tiger iron.
Opal is not crystalline so is classed as a mineraloid or amorphous solid. To be described as a mineral a naturally occurring solid must have a crystal structure.
Precious opals are fragile so need to be looked after very carefully.
The opal in the photo at the top is from Andamooka in Southern Australia. It's on display in the Natural History Museum Los Angeles. The second photo of opal in petrified wood is in the same place. Both photos are clickable and redirect to the original non-compressed image. Photos courtesy of Stan Celestian.
The links in the first section of our article redirect to photos of three stunning opals.