2020年北京文博會精品推薦
歐泊是世上最美麗和最珍貴的寶石之一，世界上95%的歐泊出產(chǎn)在澳大利亞。歐泊的化學(xué)成分組成是SiO2˙nH2O（二氧化硅水合物）。根據(jù)歐泊胚體色調(diào)的顯示，它可以分為無色、白色、淺灰、深灰一直到黑色。不同于其它寶石的是，歐泊所具有迷人的色彩是根據(jù)隨機的“變色游戲”來呈現(xiàn)光譜中各種色彩的。
歐泊是凝膠狀或液體的硅石留入地層裂縫和洞穴中沉積凝固成無定形的非晶體寶石礦，其中也包含動植物殘留物，例如樹木、甲殼和骨頭等。在高等級5歐泊中的含水率可高達(dá)到10%。
在歐泊形成過程中，二氧化硅溶液猶如巖漿流入內(nèi)陸地層的縫隙和空礦地帶沉積。沉積作用發(fā)生在距地表約四十米深處,大約每五百萬年沉積物會加一厘米的厚度。這個階段以后的一、二百萬年期間隨著氣候變化沉積物開始慢慢凝固。歐泊是沒有黏結(jié)在其他沉積物上、又過了相當(dāng)長的時間才堅硬的部分。
我們通常將天然歐泊分為兩大類：“普萊修斯歐泊”和“普通歐泊”。普萊修斯歐泊色澤明亮、能呈現(xiàn)出充分的變色效應(yīng)，比較稀有和珍貴。色澤暗淡、不能呈現(xiàn)變色效應(yīng)的稱為普通歐泊，普通歐泊在世界各地都有發(fā)現(xiàn)和少量出產(chǎn)。
在歐泊礦區(qū)開采出來的歐泊中95%都是普通歐泊，通常只有白的、灰的或者黑的一種顏色。它們只適合做“德博萊歐泊”和“翠博萊歐泊”的背景襯石。剩下的5%中是有一些色彩的等級歐泊，不過其中的95%也只是普通的等級。也就是說，開采量中只有大約0.25%才可以稱做真正有價值的歐泊。
普萊修斯歐泊被定義為會變色游戲的硅蛋白石。術(shù)語“變色游戲”是專門用來形容珍貴歐泊美麗絕倫之變幻色彩的。澳大利亞出產(chǎn)的歐泊有時也被稱為“沉積的寶石”是因為它主要形成和出產(chǎn)于中生代大自流井盆地中的沉積巖中。普萊修斯歐泊通常含有6-10%的水分，同時它所包含的小硅粒被排布成有規(guī)則的圖案。比重主要根據(jù)含水率不同在1.9-2.3之間。
硅石凝結(jié)過程中，水分逐漸減少，凝膠形成球體狀，球狀體自然附著小粒的硅石，這些無定型硅粒的尺寸在1500埃到3500埃（1埃等于一億分之一厘米）。這些球粒雖然很小，但是布滿了歐泊內(nèi)部，十分規(guī)則的排列著。由于它們是圓的球體，從結(jié)構(gòu)上來說有很小的空隙（好像很多大理石圓球被放置在容器中后出它們之間的空隙），這些空隙是三維排列的。歐泊的色彩正是由于這些規(guī)則排列的空隙通過光學(xué)衍射作用分解白光產(chǎn)生的。當(dāng)硅粒比較大的時候，空隙相對也會比較大，紅色或橙色的衍射光線就會出現(xiàn)。如果硅粒比較小，同樣空隙就會比較小，藍(lán)紫色的光譜就通過衍射作用被分解出來。其中的色彩過度就如同彩虹變化一般，光線衍射作用最強的是空隙尺寸最大的，因此紅色變彩的歐泊表面往往很明亮，而藍(lán)色變彩則相對比較暗淡。
總之，普萊休斯歐泊的色彩變化來自于規(guī)則排列的硅粒和之間空隙對白光的衍射作用。硅粒的直徑?jīng)Q定了歐泊顏色的分布范圍，小的硅粒會使歐泊產(chǎn)生通常的藍(lán)紫色，反之會產(chǎn)生珍貴的紅色。每一枚歐泊根據(jù)自身品質(zhì)都具有不同的價值，主要的決定因素是：胚體色調(diào)、變色游戲、顏色、明亮度；圖案、尺寸和形狀等。
Opal is one of the most beautiful and precious gems in the world. 95% of the world's opals are produced in Australia. The chemical composition of Opal is SiO2˙nH2O (silica hydrate). According to the hue of the opal embryo body, it can be divided into colorless, white, light gray, dark gray and black. Unlike other gems, Opal's fascinating colors are based on random "color-changing games" to present various colors in the spectrum.
Opal is a gel-like or liquid silica that is left in formation fissures and caves to deposit and solidify into an amorphous amorphous gemstone mine, which also contains animal and plant residues, such as trees, carapace, and bones. The water content in high-grade 5 opals can be as high as 10%.
During the formation of Opal, the silica solution was like magma flowing into the crevices of the inland layer and deposited in the empty mine zone. Sedimentation takes place at a depth of about 40 meters from the surface, and the sediment will add one centimeter in thickness every five million years. During the next one or two million years after this period, the sediment began to slowly solidify with climate change. Opal is a hard part that does not stick to other sediments and takes a long time.
We usually divide natural opal into two categories: "Plausius Opal" and "General Opal". Pleasant Opal is bright in color and can exhibit sufficient color change effect, which is relatively rare and precious. The dull color, which can not show the effect of discoloration, is called ordinary opal. Ordinary opal is found all over the world and produced in small quantities.
95% of the opals mined in the opal mining area are ordinary opals, usually only white, gray or black. They are only suitable for the background lining of "De Bole Opal" and "Tribble Opal". Of the remaining 5%, there are some grades of opal, but 95% of them are only ordinary grades. In other words, only about 0.25% of the mining volume can be called a truly valuable opal.
Pleasant Opal is defined as a silicon opal that can change color. The term "color-changing game" is specifically used to describe the beautiful and changing colors of precious opal. The Opal produced in Australia is sometimes referred to as "deposited gemstone" because it is mainly formed and produced in the sedimentary rocks in the Mesozoic large artesian well basin. Plausius Opal usually contains 6-10% moisture, and the small silicon particles it contains are arranged in a regular pattern. The specific gravity is mainly between 1.9-2.3 according to the moisture content.
During the condensation of silica, the water gradually decreases, and the gel forms a sphere. The spheres naturally adhere to small particles of silica. The size of these amorphous silicon particles is 1500 to 3500 Angstroms (1 Angstrom is equal to one hundred millionth of a centimeter). Although these pellets are small, they are filled with opal and arranged in a very regular manner. Because they are round spheres, there are very small voids in structure (it seems that many marble round balls are placed in the container to leave the gap between them). These voids are arranged in three dimensions. Opal's color is caused by the regular diffraction of these white light through optical diffraction. When the silicon particles are relatively large, the gap will be relatively large, and red or orange diffracted light will appear. If the silicon particles are smaller, the gaps will be smaller, and the blue-violet spectrum will be decomposed by diffraction. The excessive color is like a rainbow change. The strongest light diffraction effect is the largest gap size. Therefore, the red-colored opal surface is often very bright, while the blue-colored change is relatively dim.
In short, the color change of Plessius Opal comes from the diffraction effect of regularly arranged silicon particles and the gaps between them on white light. The diameter of the silicon particles determines the distribution range of the opal color. Small silicon particles will cause the opal to produce the usual blue-violet, otherwise it will produce a precious red. Each opal has different values according to its own quality. The main determinants are: hue of embryo body, color change game, color, brightness; pattern, size and shape.
2020年5月28日
