本篇文章共分 7 段，將礦物的物理性質，從其晶體結構、顏色、光澤、條痕、硬度、以及解理等特徵一一加以說明陳述。

本篇考題英文原文與對應之中文翻譯整理如下。練習作答解題時若有對語意不清楚之處，請仔細查閱對照，以提升閱讀理解能力。

Physical Properties of Minerals 礦物的物理特性

1. 礦物的物理性質

   A mineral is a naturally occurring solid formed by inorganic processes. Since the internal structure and chemical composition of a mineral are difficult to determine without the aid of sophisticated tests and apparatus, the more easily recognized physical properties are used in identification.

   礦物是一種自然形成的固體，由無機過程形成。由於礦物的內部結構和化學成分在沒有複雜的測試和儀器的幫助下很難確定，因此在鑒定時使用更容易識別的物理性質。

2. 晶體結構

   Most people think of a crystal as a rare commodity, when in fact most inorganic solid objects are composed of crystals. The reason for this misconception is that most crystals do not exhibit their crystal form: the external form of a mineral that reflects the orderly internal arrangement of its atoms. Whenever a mineral forms without space restrictions, individual crystals with well-formed crystal faces will develop. Some crystals, such as those of the mineral quartz, have a very distinctive crystal form that can be helpful in identification. However, most of the time, crystal growth is interrupted because of competition for space, resulting in an intergrown mass of crystals, none of which exhibits crystal form.

   大多數人認為水晶是一種稀有商品，而事實上大多數無機固體物體都是由晶體組成的。造成這種誤解的原因是，大多數晶體並沒有表現出它們的晶體形態：礦物的外部形態反映了其原子的內部有序排列。每當一種礦物在沒有空間限制的情況下形成時，就會形成具有良好晶面的個別晶體。有些晶體，如礦物石英的晶體，具有非常獨特的晶體形態，可以幫助識別。然而，在大多數情況下，由於對空間的競爭，晶體的生長會被打斷，導致晶體的交錯生長，其中沒有一個表現出晶體形態。

3. 礦物的顏色

   Although color is an obvious feature of a mineral, it is often an unreliable diagnostic property. Slight impurities in the common mineral quartz, for example, give it a variety of colors, including pink, purple (amethyst), white, and even black. When a mineral, such as quartz, exhibits a variety of colors, it is said to possess exotic coloration. Exotic coloration is usually caused by the inclusion of impurities, such as foreign ions, in the crystalline structure. Other minerals—for example, sulfur, which is yellow, and malachite, which is bright green—are said to have inherent coloration because their color is a consequence of their chemical makeup and does not vary significantly.

   雖然顏色是礦物的一個明顯特徵，但它往往是一個不可靠的診斷特性。例如，普通礦物石英中的輕微雜質使其具有各種顏色，包括粉紅色、紫色（紫水晶）、白色，甚至黑色。當一種礦物，如石英，表現出各種顏色時，它被說成是具有異國色彩。異色通常是由於在晶體結構中含有雜質，如外來離子，而造成的。其他礦物—例如黃色的硫磺和鮮綠色的孔雀石—被稱為具有固有的顏色，因為它們的顏色是其化學構成的結果，同時不會產生明顯的變化。

4. 礦物的條痕

   Streak is the color of a mineral in its powdered form and is obtained by rubbing a mineral across a plate of unglazed porcelain. Whereas the color of a mineral often varies from sample to sample, the streak usually does not and is therefore the more reliable property.

   條痕是礦物在其粉狀形式下的顏色，是通過在未上釉的瓷板上摩擦礦物而獲得的。礦物的顏色往往因樣品而異，而條痕通常不會，因此是更可靠的屬性。

5. 礦物的光澤

   Luster is the appearance or quality of light reflected from the surface of a mineral. Minerals that have the appearance of metals, regardless of color, are said to have a metallic luster. Minerals with a nonmetallic luster are described by various adjectives, including vitreous (glassy), pearly, silky, resinous, and earthy (dull).

   光澤是指從礦物表面反射的光線的外觀或性質。具有金屬外觀的礦物，無論其顏色如何，都被稱為具有金屬光澤。具有非金屬光澤的礦物用各種形容詞來描述，包括玻璃質（玻璃狀）、珍珠質、絲質、樹脂質和土質（暗淡）。

6. 礦物的硬度

   One of the most useful diagnostic properties of a mineral is hardness, the resistance of a mineral to abrasion or scratching. This property is determined by rubbing a mineral of unknown hardness against one of known hardness, or vice versa. A numerical value can be obtained by using Mohs' scale of hardness, which consists of ten minerals arranged in order from talc, the softest, at number one, to diamond, the hardest, at number ten. Any mineral of unknown hardness can be compared with these or with other objects of known hardness. For example, a fingernail has a hardness of 2.5, a copper penny 5, and a piece of glass 5.5. The mineral gypsum, which has a hardness of two, can be easily scratched with your fingernail. On the other hand, the mineral calcite, which has a hardness of three, will scratch your fingernail but will not scratch glass. Quartz, the hardest of the common minerals, will scratch a glass plate.

   礦物最有用的診斷特性之一是硬度，即礦物對磨損或刮傷的抵抗力。這一特性是通過將未知硬度的礦物與已知硬度的礦物進行摩擦來確定的，反之亦然。使用莫氏硬度計可以得到一個數值，莫氏硬度計由十種礦物組成，從最軟的滑石（1 號）到最硬的鑽石（10 號），依次排列。任何未知硬度的礦物都可以與這些礦物或其他已知硬度的物體進行比較。例如，一個指甲的硬度是 2.5，一個銅錢的硬度是 5，一塊玻璃的硬度是 5.5。礦物石膏的硬度為 2，可以很容易地用手指甲留下劃痕。另一方面，硬度為 3 的礦物方解石會刮花你的指甲，但不會劃傷玻璃。石英是最硬的普通礦物，會刮傷玻璃板。

7. 礦物的解理

   The tendency of a mineral to break along planes of weak bonding is called cleavage. Minerals that possess cleavage are identified by the smooth, flat surfaces produced when the mineral is broken. The simplest type of cleavage is exhibited by the micas. Because the micas have excellent cleavage in one direction, they break to form thin, flat sheets. Some minerals have several cleavage planes, which produce smooth surfaces when broken, while others exhibit poor cleavage, and still others exhibit no cleavage at all. When minerals break evenly in more than one direction, cleavage is described by the number of planes exhibited and the angles at which they meet. Cleavage should not be confused with crystal form. When a mineral exhibits cleavage, it will break into pieces that have the same configuration as the original sample does. By contrast, quartz crystals do not have cleavage, and if broken, would shatter into shapes that do not resemble each other or the original crystals. Minerals that do not exhibit cleavage are said to fracture when broken. Some break into pieces with smooth curved surfaces resembling broken glass. Others break into splinters or fibers, but most fracture irregularly.

   礦物沿著薄弱的結合面斷裂的傾向被稱為解理。擁有解理的礦物可通過礦物破碎時產生的光滑、平坦的表面來識別。最簡單的解理類型是由雲母表現出來的。因為雲母在某一個方向上有很好的解理，所以它們斷裂後會形成薄而平的薄片。一些礦物有幾個解理面，在破碎時產生光滑的表面，而其他礦物則表現出較差的解理，還有一些礦物根本沒有解理。當礦物向一個以上的方向均勻斷裂時，解理是由所表現出的平面數量和它們相交的角度來描述。解理不應與晶體形態相混淆。當一種礦物表現出解理時，它將斷裂成與原始樣品具有相同構造的碎片。相比之下，石英晶體沒有解理，如果被打破，會破碎成彼此不相似的形狀，也不像原來的晶體。沒有解理的礦物在破碎時據說會斷裂。有些礦物會破碎成表面光滑的曲線，類似於破碎的玻璃。另一些則斷成碎片或纖維，但大多數斷裂是不規則的。