Chocolate Opal Gemstone Information
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About Chocolate Opal – History and Introduction
In 1939, British anthropologist, archeologist and naturalist, Louis Leakey, claimed that opal mines existed in ancient Africa. His claims were based on his discovery of tools that were made using opal components. He claimed to have made the astonishing discovery in ancient Kenyan caves during one of his explorations. It was not until later that the relics he had discovered were proclaimed to be astonishingly old, dating back to 4000 years B.C.
Recently in 1994, another fellow geologist and scientist, Dr. N. Barot, validated Leakey's claims of opal mines existing in ancient Africa. Dr. Barot was fortunate enough to witness Ethiopian opals being openly traded in Nairobi. It was because of Dr. Barot's reports that another avid fellow 'mineralist', Telahun Yohannes, began his quest for Ethiopian opal. Yohannes singlehandedly initiated the exploration and mining for Ethiopian opal, putting Ethiopia on the map as one of the world's top opal sources and the only source for the specific variety of chocolate opal.
Chocolate opal is one of the many different varieties of opal available. The unique and distinct chocolate color is what separates this variety from other opal varieties. The dark base colors of chocolate opal can range from light to dark chocolate brown colors. The darker tones allow for more intense play of color which is the most valued trait when identifying fine precious opal. No other colored gemstone is able to replicate the illusive and mystical properties of chocolate opal and its play of color.
Often the term 'opalescence' is misused to describe chocolate opal's unique and distinct play of color. Opalescence should technically only be used to identify and describe common opal (also known as 'potch') which does not possess any play of color.
Chocolate opal is of volcanic nature. It is found and formed within layers of developed volcanic ash and grouped in clusters of nodules. Despite having fire-like characteristics, chocolate opals are deposited at relatively low temperature levels, unlike other fire-rocks born of igneous passage.
Chocolate opal is found and mined solely from Yita Ridge, which is located approximately 150 miles northeast of Ethiopia's capital, Addis Ababa. The opal fields are approximately 12 miles north of Mezezo and extend along the northern face of Yita Ridge. Surprisingly, there are only a few square miles of opal-rich fields, which contain all of Ethiopia's opals. Opal production and extraction is restricted to only this small region in Mezezo, and because of this, the supply of chocolate opal is extremely limited; a sheer testament to its rarity.
Sources for other opal varieties include the United States, Czech Republic, Slovakia, Turkey, Hungary, Indonesia, Honduras, Guatemala, Nicaragua and Brazil. The most unusual and rarest opal source was recently discovered in 2008 by NASA. Surprisingly, opal deposits were discovered on Mars during one of their space explorations. Australia is very well-known as being the top producer of fine quaility opal, producing well over 90% of the entire world's opal supply.
There are many different varieties of opal available, but all of the different types can be classified as either 'precious opal' or 'common opal'. Opal is sometimes mistaken for ammonite, labradorite, mother-of-pearl or moonstone, but through proper testing, it is easily distinguishable from lookalikes. Precious opal can be found layered and mounted with more common opal, or other stones such as chalcedony quartz. These opals are sold under the trade name, 'opal doublets' or 'layer opal'. 'opal triplets' are the same as opal doublets, but they contain a third layer of crystal mounted mainly for protection.
The term 'opal' was derived from an ancient Indian (Sanskrit) word "upala", meaning "valuable stone". Upala is believed to have originated from the Greek word, "opallios", which means "color change". During ancient Roman times, opal was referred to as "opalus", which means "stone from several elements".
According to an old Australian Aboriginal legend, the creator came down from the heavens on a rainbow and delivered a message of peace for all mankind. The stones that were near the place where his foot touched the ground suddenly became alive and began to sparkle. This encounter was believed to have been the birth of all opals.
Opal is believed to have many legendary healing powers. It has been used by many cultures for the practice of alternative crystal healing. For those who believe in the power of opal, it is said to be able to cure depression and help find true love. Since the Middle Ages, opal was known as 'opthalmius', or the 'eye stone'. Still to this day, opal is used to alleviate eye pain and to strengthen one's vision.
There are several advantages of buying loose gemstones (rather than preset jewelry). First, once a gemstone has been set, it is difficult to know the actual quality of the stone. Jewelry settings can often hide or obscure blemishes and you may be misled into believing that the stones are better quality than they actually are. Loose gemstones offer a greater variety and choice, but most importantly, buying loose gemstones saves money.
Chocolate opals, despite being soft and fragile, are often used in cabochon gemstone rings. Opals are one of the preferred stones for gentlemen, especially those with darker colors because they represent a certain level of masculinity. Chocolate opal is also very popular for pendants, earrings, brooches and pins. They can make interesting accessories for men including cufflinks, tie-tacks and money clips. Due to the wide range of colors that chocolate opal gemstones can display, they can be ideally set into any type of precious metal. Heavier, protective style mountings are recommended and ideal for added durability.
Opals are considered delicate gemstones. Their most significant weakness is a result of their high water content. Opals can dry out and eventually crack or fade if not properly cared for. They are also sensitive to sudden or extreme temperature changes. It is recommended that opals are stored in a sealed plastic bag containing a source of moisture, such as a damp cloth or cotton-ball in order to prevent dehydration and crazing.
Opal hardness ranges from 5.5 to 6.5 on the Mohs scale, so they are fairly soft and can scratch easily. Ordinary dust often contains traces of quartz, so simply wiping dust off your opal can cause scratches and damage the polish. Opal should be cleaned using a soft clean cloth. Dust particles should be removed by rinsing with room-temperature water. Never use any bleach or chemicals and do not use any ultrasonic cleaners because the vibrations alone can cause an opal to crack. Always remove opal jewelry when engaging in household chores or vigorous physical activities.
Damaged opals are extremely difficult to repair and it may be better to replace one, rather than repairing it. Current opal repair methods are only experimental and no official technique has been developed or approved. The most common repair methods require impregnating damaged opals with polymers or resins.
- 初刊: June-13-2013
- 最終アップデート: January-16-2019
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