无机非金属材料专业英语-宝石材料地质的介绍

1、Unit 26 An Introduction to the Geology of Gem Materials宝石材料地质的介绍n1、The division of the sciences into various subjects, such as biology, chemistry, geology and physics, is convenient for their study, and for teaching purposes. n为了方便研究和教学，科学可以划分为不同的学科，如生物学、化学、地质学和物理学。 nTo study any of these subjects e

2、ffectively, the student should have, at least, some knowledge and understanding of the related sciences.n为了有效学习任何一个学科，学生至少必须具备相关科学的一些知识和理解。 n Gemology is no exception to this and a basic understanding of the geology and mineralogy of gemstones will be helpful.n宝石学也不例外，具备基本的宝石的矿物学和地质学的基本知识对学习宝石学非常有帮助

3、。The Crust（地壳）（地壳）n2、The solid crust of the continents on which we live varies from about 25km (15 miles) to about 70km (45 miles) in thickness. n我们居住的陆地固体壳层厚度大约是25km到70km。 nUnder the oceans it averages about 6km (4 miles).n海洋下厚度平均约为6km。n3、Much of the crust has a thin covering composed chiefly of se

4、dimentary material. n大部分壳层由一层稀薄的主要由沉积岩材料组成的包覆层。 nThis is material, which has been deposited by wind, rain, and seawater or by chemical precipitation, and then cemented or compressed to form rocks. n这些材料是由风、雨和海水沉积而成，或者是化学沉积，而后胶凝或压实形成岩石。 nThese sedimentary rocks are chiefly limestone, clay, shale and

5、sandstone.n这些沉积岩主要是石灰岩、黏土、页岩和砂岩。n4、Granites, basalt and metamorphic rocks form the major part of the crust (the middle and lower layers). n花岗岩，玄武岩和变质岩形成了地壳（中间和底层）的重要组成部分。 nThe first two have been formed by the solidification of molten rock and are termed igneous rocks. n前两个由熔岩凝固形成，被称为“岩浆岩”岩石。 nMetam

6、orphic rocks are any rocks that have undergone change (metamorphism), principally by heat or pressure in the depths of the earth.n变质岩是经历了变质作用而成的普通的岩石，主要是由于在地球深处的热或压力所致。n5、The middle layer of the crust varies between 16 and 24km (1015 miles) in thickness, beneath the continental landmasses. n地壳的中间层的厚

7、度在16至24km不等（1015英里），在大陆陆地的下方。 nIt is sometimes referred to as granitic layer, as granite is its main constituent.n n它有时被称为“花岗岩层”因为花岗岩是它的主要成分。 nSimilarly the lower layer is known as the basaltic layer, as basalt and other basic rocks predominate.n同样，低层被称为“玄武岩层”，因为以为玄武岩和其他基本岩为主。n6、In the Atlantic, the

8、 Pacific and other major oceans, the crust is very thin, and its major component is the basaltic layer. n在大西洋，太平洋和其他主要海洋，地壳很薄，它的主要成分是玄武岩层。The Intermediate Zone or Mantle（过渡区或地幔）（过渡区或地幔）n7、Beneath the crust lies the mantle with a thickness of about 2900km (1800 miles).n位于下方的地壳的地幔厚度约为约2900km（厚度1800英里）

9、。nIt is hot and plastic, in contrast to the cooler and more rigid crust.n和冰冷刚硬的地壳相比它是热的而且具有塑性。The Core（地心，中心）（地心，中心）n8、The core extends about 3500km (2150 miles), from the mantle to the center of the Earth.n地心从地幔到地球中心延伸大概至3500km。nScientists are uncertain as to its temperature and its composition.n关于

10、它的温度和组成科学家都是不确定的。n9、One theory is that it is chiefly composed of molten nickel and iron (partly solid, partly molten). (Using the chemical symbols for these two elements, Ni and Fe respectively, geologists sometimes call this portion of the Earth, NIFE. )n一种理论说它主要是由熔融的镍和铁组成（部分溶解部分还是固体）（分别用化学式Ni和Fe来表

11、示，地质学家有时称地球的这部分为NIFE）n10、The core, mantle and crust each have different physical characteristics. n中心、地幔和地壳分别具有不同的物理性质。 n The core is under the highest pressure, and its temperature is higher than those of the mantle and crust. Because of these differences there are discontinuities and relative move

12、ment between these regions n中心温度最高，它的温度高于地幔和地壳。由于这些不同导致这些区域间中断和相对运动。n11、It is these factors, together with the effects of gravity and the forces exerted by the other members of our solar system, that are considered to be responsible for such natural phenomena as volcanic eruptions, earthquakes, the

13、slow drift of the continents and the buckling of the surface of the Earth to form mountain ranges and valleys.n以上这些因素以及万有引力和太阳系其它星球施加的力被认为是形成这些自然现象如火山喷发、地震、板块移动和地球板块挤压形成山脉和流域的原因。n12、The surface features of the Earth are produced by two sets of opposing forces - destructive and constructive.n地球地貌由两种相

14、反作用力产生：破坏性的和建设性的。n13、The destructive forces, such as those due to wind, rain, rivers, glaciers, the action of the sea and some earthquakes, continuously break down the rocks, and minerals, which form the features of the Earths crust. n破坏力如由风、雨、河流、冰川、海洋和一些地震引起的力会连续不断的破坏岩石和矿物质，这些都是形成地壳形貌的因素。 nThis is

15、a slow never-ending process.n这是一个缓慢的无休止的过程。n14、The constructive forces , due to such Earth movements as the drift of the landmasses (plate tectonics) and volcanic activities, are continually forming new features. n由于地球运动所致，如地幔漂移（板块构造学）和火山活动，建设性力会持续形成新的形貌。 nSome of these changes may be relatively rap

16、id, as in the case of volcanoes, whilst others may take millions of years, as with the gradual movement of the continents. n其中的一些变化可能相对较快，比例火山，其它的可能会需要数百年，如大陆板块的持续移动。nNevertheless, the formation is continuous.n不管怎样，构造是持续的。The Composition of the Earth（地球组成）（地球组成）n15、There are 92 naturally occurring e

17、lements in the Earths crust and, of those, eight account for approximately 98% of the crust. n有92个天然元素存在于地壳中，其中，八种元素占了地壳的大约98%。 nThey are oxygen (46.6% ), silicon (27.2% ), aluminum (8.1 %), iron (5.0%), calcium (3.6%), sodium (2.8%), potassium (2.6%) and magnesium (2.1%).n它们是氧（46.6），硅（27.2），铝（8.1），

18、铁（5.0），钙（3.6），钠（2.8），钾（2.6）和镁（2.1 ）。 n16、It should be realized, however, that the elements forming the Earth are not evenly distributed through the crust, for example basalt has a composition different from granite, and both these differ from limestone.n然而，应该看到，这些构成地球的元素并非均匀分布的，例如由玄武岩组成和花岗岩不同，这两种和石灰

19、岩又都不同。n17、These natural elements combine together chemically to form compounds and some of these chemical compounds are minerals.n这些自然元素经过化学作用结合在一起形成化合物，其中的一些化合物是矿物质。n18、A mineral, in most cases, is a naturally formed inorganic substance, which possesses a definite chemical composition and a definit

20、e atomic structure.n在大多数情况下，一种矿物质是自然形成的无机物，这种无机物具有确定的化学成分和确定的原子结构。n19、A mineral may consist of just one element (e. g. diamond is composed of just one element - carbon) or of several elements, chemically combined to form a compound (e. g. quartz is a compound made up of silicon and oxygen atoms).n一种矿物质可能只有一种元素组成，如金刚石只有碳元素组成，或者由几种元素组成，化学结合形成化合物，例如石英就是由氧原子和硅原子组成的化合物。n20、Rocks, however, consist of mine