What Is Opal and What Is It Made Of

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Opal is a non-crystalline form of mineral silica. Opal is related to the more common crystalline cousins such as quartz and agate. Opal differs as it is formed from amorphous lumps of silica rather than that from naturally faceted crystals. The chemical composition of opal is SiO2H2O, silicon dioxide combined with water (an opal stone may contain up to 30% water.) Opal’s Moh’s hardness rating is measured at 6.0 to 6.5 on the scale similar in hardness to quartz. Most opal is more than 65 million to 145 million years old and is found in the Cretaceous layer of rock which was during the period when dinosaurs roamed the earth.

Opal tends to be found near the earth’s surface in areas where ancient geothermal hot springs once flowed. The minerals bubbled up from beneath the surface of the earth and slowly over centuries lined the walls of cavities in the bedrock. More than 90% of the world’s quality gem opals come from Southern Australia, although it can be found in other parts of the world such as Ethiopia, Brazil, Mexico, Czechoslovakia and Nevada. All black opal comes exclusively from Australia.

To define opal in layman terms, it is a solid gem mineraloid (has mineral characteristics, but is not one) that is solidified from the chemical silicon dioxide, which come from cavities in decaying vegetation, wood, and bones. In science mode, opal is known as SiO2·nH2O, mixing silicon dioxide with water. Unlike other gems, opal comes in many varieties – white, blue, red, black, and even colorless. Its most unique character is that it displays all the colors of the spectrum resulting from the interference and diffraction of light passing through it. In other words, the bright rainbow look of opal, as they appear to the when seen, will move and change dramatically depending on the angle at which the stone is viewed.

Opal Varieties

There are two main varieties of opal - precious and common. Precious opals exhibit the characteristic called “play-of-color,” and are comparatively rare. Common opal is dull and valueless and occurs in abundance throughout the world. Common opal does not exhibit a play of color. When common opal is found in association with precious opal, it is known as potch. About 95% of all opal mined from the opal fields are common or potch, basically one colored. The remaining 5% has some color, but about 95% of it is of mediocre grade. Therefore, only approximately 0.25% has any real value at all. The other kinds of opal include Fire Opal, which is transparent to translucent, a blue opal known as Peruvian Opal, and Girasol opal, which comes from Mexico mainly, and exhibits a bluish glow or sheen that follows the light source around which is not a play of color.

Opal Is Sedimentary

Opal is one of the few gemstones that are sedimentary in origin. Opal still contains 6 to 10 percent water, a remnant of that ancient sea. Gold panners in Australia found the first few pieces of precious opal in 1863. A large percentage of the world’s stable commercial opal comes from Australia, and there are three distinctive regions where opal comes from. These are Lightning Ridge (the home of black opal) the South Australian fields Coober Pedy, Mintabie, Lambina and Andamooka (the main sources of light base opal) and the Queensland fields, where boulder opal originates.

Opalescence

The most striking feature of opal is the ability to refract and reflect specific wavelengths of colours. In fact, the term “opalescence” was coined to describe this phenomenon. The size and spacing of the amorphous spheres of silica within the stone refracts specific wavelengths of light; each sphere refracting a single, pure spectral colour much like the droplets of water in a rainbow. The interplay of these pure wavelengths of light gives opal its unique visual appeal and makes it one of the most sought-after gemstones in the world.

History Of Opal

Opals contain the wonders of the skies - sparkling rainbows, fireworks and lightning. Like the sky the opal colours shift and flash with movement, the combination of colours and patterns means every opal is unique. Black opal was first discovered in Australia in the late 1800s. Before its discovery the world was only aware of crystal opal which was typically mined in Eastern Europe. Many royal families throughout history have treasured opal particularly in Europe and Africa. The oldest recorded opal was found by the famous archaeologist Louis Leakey who found six thousand year old opal artifacts in a cave in Kenya! The Roman historian Pliny rightfully described opal as the queen of gems, as opal is a combination of the beauty of all other gems: “There is in them a softer fire than the ruby, there is the brilliant purple of the amethyst, and the sea green of the emerald - all shining together in incredible union. Some by their splendour rival the colours of the painters, others the flame of burning sulphur or of fire quickened by oil.”

Opals have been popular with some of the greatest names in history including Cleopatra and Marc Anthony. One of Marc Anthony’s fellow Roman senators owned an opal stone that reminded Marc of Cleopatra so much that he had to have it. When the Senator refused to sell it to him he sent him into exile.The French Emperor Napoleon was more successful giving Josephine a beautiful opal with brilliant red flashes called “The burning of Troy,” making her his Helen.

Opals were also famous in literature. Shakespeare likening the opals play of colour to play of mind in the most famous use of gemstone symbolism in literature. In Twelfth Night, he writes: “Now the melancholy God protect thee, and the tailor make thy garments of changeable taffeta, for thy mind is opal.” For a few centuries opals seemed to disappear from history. However in modern times Queen Victoria reignited interest in the gemstone. Queen Victoria loved opals and often gave them as wedding presents. She and her daughters created a fashion trend for the wearing of Opal.

Queen Victoria was one of the first to appreciate opals from an exciting new source: Australia. The story of Australian opal begins more than 100 million years ago, when the deserts of central Australia were a great Inland Sea, with silica-laden sediment deposited around its shoreline. After the sea receded and disappeared to become the great Artesian basin, weathering 30 million years ago released a lot of the silica into a solution which filled cracks in the rocks, layers in clay, and even some fossils. Some of this silica became precious opal.

Australian Opal

Opal is predominantly found in Australia. 95% of it, to be exact, is found there, thus making opal the country’s national gemstone. The largest and most valuable opal, the Olympic Australis, was found in 1956 in the town of Coober Pedy, a major source of opal. Other sources of opal included Ethiopia, Nevada, Idaho, and even Mars, where NASA discovered opal deposits in 2008. Ethiopian opal comes from the Wollo and North Shewa Provinces. Wollo opal, also called “Welo” or “Wello” opal, has become the dominant Ethiopian opal in the gem trade. The Smithsonian Institute has he largest unpolished and polish black opals, both from Virgin Valley, Nevada. The unpolished opal is known as the “Roebling Opal,” which was found in 1917 and weighs 2,585 carats. The polish version is called the “Black Peacock” and weights 160 carats.

The major opal producing fields for black opal is Lightning Ridge in New South Wales, Australia, and to a much lesser degree Mintabie in South Australia. The most sought after black opal is red or multicolour on black, which is very difficult to find. Such stones are always cut on the fields and sold immediately. Boulder opal is opal that is formed in a brown ironstone nodule and is distinctive because it typically presents as a thin layer of opal over a dark brown base when cut. The opal can be quite superb. Opal from Lightning Ridge is often considered to be the best and brightest in the world.

Opal is one of the worlds most beautiful and precious gemstones and is one of six types of gemstones used throughout history, along with diamonds, rubies, sapphires, emeralds, and pearls. The word ‘opal’ is adapted from the Roman term opalus, but adapted from the Sanskrit word úpala. It is also the birthstone of October, but, since the 19th century, has been associated with bad luck and death thanks to the novel Anne of Geierstein, which uses opal as a plot device. Regardless, it remains likeable and wanted by gem collectors despite the superstition around it maintain the evil eye, as it is a gorgeous collectors item for enthusiasts of such items.

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Ethiopian Opal

蛋白石是礦物二氧化矽的非結晶形式。蛋白石與更常見的晶體表親有關，如石英和瑪瑙。蛋白石的不同之處在於它是由無定形二氧化矽塊形成的，而不是由天然刻面晶體形成的。蛋白石的化學成分是 SiO2H2O、二氧化矽與水的結合（一塊蛋白石可能含有高達 30% 的水。）蛋白石的莫氏硬度等級為 6.0 至 6.5，硬度與石英相似。大多數蛋白石的歷史超過 6500 萬至 1.45 億年，發現於白堊紀岩石層中，這是恐龍在地球上漫遊的時期。

在古代地熱溫泉曾經流過的地區，往往會在地表附近發現蛋白石。礦物從地表下冒出來，幾個世紀以來慢慢地排列在基岩的空腔壁上。世界上 90% 以上的優質寶石蛋白石來自澳大利亞南部，儘管它可以在世界其他地區找到，例如埃塞俄比亞、巴西、墨西哥、捷克斯洛伐克和內華達州。所有的黑蛋白石都來自澳大利亞。

用外行術語來定義蛋白石，它是一種固體寶石礦物（具有礦物特徵，但不是礦物特徵），由化學二氧化矽固化而成，二氧化矽來自腐爛的植被、木材和骨骼中的空腔。在科學模式中，蛋白石被稱為 SiO2·nH2O，將二氧化矽與水混合。與其他寶石不同，蛋白石有多種類型——白色、藍色、紅色、黑色，甚至無色。它最獨特的特點是它顯示了通過它的光的干涉和衍射產生的光譜的所有顏色。換句話說，蛋白石明亮的彩虹外觀，當他們看到時，會根據觀察石頭的角度移動和變化。

蛋白石品種

有兩種主要的蛋白石品種——珍貴的和普通的。珍貴的蛋白石具有被稱為“遊彩”的特性，而且相對稀有。普通蛋白石暗淡無價值，在世界各地大量出現。普通蛋白石不會出現色差。當發現普通蛋白石與珍貴蛋白石相關時，它被稱為potch。從蛋白石領域開采的所有蛋白石中約有 95% 是普通的或雜色的，基本上是一種顏色。剩下的 5% 有一些顏色，但大約 95% 是中等等級的。因此，只有大約 0.25% 具有任何實際價值。其他種類的蛋白石包括火蛋白石，它是透明到半透明的，一種被稱為秘魯蛋白石的藍色蛋白石，以及主要來自墨西哥的 Girasol 蛋白石，並隨著周圍的光源而呈現出藍色的光芒或光澤。玩顏色。

蛋白石是沉積物

蛋白石是為數不多的起源於沉積的寶石之一。蛋白石仍然含有 6% 到 10% 的水，這是古代海洋的殘餘。澳大利亞淘金者在 1863 年發現了第一批珍貴的蛋白石。世界上穩定的商業蛋白石有很大一部分來自澳大利亞，而蛋白石來自三個不同的地區。它們是 Lightning Ridge（黑蛋白石的故鄉）、南澳大利亞的 Coober Pedy、Mintabie、Lambina 和 Andamooka（輕質蛋白石的主要來源）以及昆士蘭州的油田，那裡是巨石蛋白石的產地。

乳光

蛋白石最顯著的特點是能夠折射和反射特定波長的顏色。事實上，“乳光”一詞就是用來描述這種現象的。石頭內無定形二氧化矽球體的大小和間距折射特定波長的光；每個球體都折射出一種單一的純光譜顏色，就像彩虹中的水滴一樣。這些純光波長的相互作用賦予蛋白石獨特的視覺吸引力，使其成為世界上最受歡迎的寶石之一。

蛋白石的歷史

蛋白石包含天空的奇蹟 - 閃閃發光的彩虹、煙花和閃電。就像天空一樣，蛋白石的顏色隨著運動而變化和閃爍，顏色和圖案的組合意味著每塊蛋白石都是獨一無二的。黑蛋白石於 1800 年代後期首次在澳大利亞被發現。在它被發現之前，全世界只知道通常在東歐開采的水晶蛋白石。歷史上許多王室都珍視蛋白石，尤其是在歐洲和非洲。有記載的最古老的蛋白石是由著名考古學家路易斯·利基 (Louis Leakey) 發現的，他在肯尼亞的一個洞穴中發現了 6000 年曆史的蛋白石文物！羅馬歷史學家普林尼正確地將蛋白石描述為寶石中的皇后，因為蛋白石是所有其他寶石之美的結合：“它們比紅寶石更柔和，有紫水晶的絢麗紫色，還有大海祖母綠的綠色 - 所有這些都以令人難以置信的結合一起閃耀。有的色彩絢麗，堪比畫家的色彩，有的則是硫磺燃燒的火焰，或油激起的火光。”

蛋白石一直受到歷史上一些最偉大的名字的歡迎，包括克利奧帕特拉 (Cleopatra) 和馬克·安東尼 (Marc Anthony)。馬克·安東尼的一位羅馬參議員同胞擁有一塊蛋白石，讓馬克想起了克利奧帕特拉，以至於他不得不擁有它。當參議員拒絕將其出售給他時，他將他流放了。法國皇帝拿破崙更成功地給了約瑟芬一顆美麗的蛋白石，帶有明亮的紅色閃光，稱為“特洛伊的燃燒”，使她成為他的海倫。

蛋白石在文學中也很有名。莎士比亞在文學中最著名的寶石像徵用法中，將蛋白石的色彩遊戲比作心靈遊戲。在第十二夜，他寫道：“現在憂鬱的上帝保護你，裁縫用多變的塔夫綢做你的衣服，因為你的心是蛋白石。”幾個世紀以來，蛋白石似乎從歷史中消失了。然而，在現代，維多利亞女王重新點燃了對寶石的興趣。維多利亞女王喜歡蛋白石，經常將它們作為結婚禮物贈送。她和她的女兒們開創了佩戴蛋白石的時尚潮流。

維多利亞女王是最早欣賞來自令人興奮的新產地：澳大利亞的蛋白石的人之一。澳大利亞蛋白石的故事始於 1 億多年前，當時澳大利亞中部的沙漠是一片巨大的內海，其海岸線周圍沉積著富含二氧化矽的沉積物。在海水退去並消失成為大自流盆地之後，3000 萬年前的風化將大量二氧化矽釋放到溶液中，填充了岩石裂縫、粘土層，甚至一些化石。其中一些二氧化矽變成了珍貴的蛋白石。

澳大利亞蛋白石

蛋白石主要產於澳大利亞。準確地說，其中 95% 都在那裡發現，從而使蛋白石成為該國的國石。最大和最有價值的蛋白石，Olympic Australis，於 1956 年在蛋白石的主要產地 Coober Pedy 鎮被發現。蛋白石的其他來源包括埃塞俄比亞、內華達州、愛達荷州，甚至火星，NASA 於 2008 年在那裡發現了蛋白石礦床。埃塞俄比亞蛋白石來自 Wollo 和 North Shewa 省。 Wollo 蛋白石，也稱為“Welo”或“Wello”蛋白石，已成為寶石貿易中占主導地位的埃塞俄比亞蛋白石。史密森學會擁有最大的未拋光和拋光黑色蛋白石，均來自內華達州維爾京谷。未經拋光的蛋白石被稱為“羅布林蛋白石”，發現於 1917 年，重 2,585 克拉。波蘭版本被稱為“黑孔雀”，重 160 克拉。

黑蛋白石的主要蛋白石產區是澳大利亞新南威爾士州的 Lightning Ridge，南澳大利亞州 Mintabie 的產地要小得多。最受追捧的黑蛋白石是黑色上的紅色或多色，很難找到。這樣的石頭總是在田野上切割並立即出售。博爾德蛋白石是形成於棕色鐵礦石結節中的蛋白石，其獨特之處在於切割時通常在深棕色基底上呈現一層薄薄的蛋白石。蛋白石可以非常棒。閃電嶺的蛋白石通常被認為是世界上最好、最亮的。

蛋白石是世界上最美麗、最珍貴的寶石之一，是歷史上使用的六種寶石之一，還有鑽石、紅寶石、藍寶石、祖母綠和珍珠。 “蛋白石”一詞改編自羅馬術語 opalus，但改編自梵文單詞 úpala。它也是十月的誕生石，但自 19 世紀以來，由於使用蛋白石作為情節設計的小說蓋爾斯坦的安妮，它一直與厄運和死亡聯繫在一起。無論如何，儘管圍繞它的迷信保持邪惡的眼光，但它仍然受到寶石收藏家的喜愛和追捧，因為它是此類物品愛好者的華麗收藏品。