📚 Rocks and Minerals: IB WJEC Science Key Concepts | IB WJEC 科学：岩石与矿物考点精讲
Rocks and minerals form the solid foundation of our planet, driving geological processes and providing essential resources. In IB and WJEC science courses, you need to understand mineral properties, rock classification, the rock cycle, and how to identify common specimens. This revision guide breaks down the core ideas, offering clear explanations and exam-focused insights for both syllabuses.
岩石和矿物构成了我们星球的固体基础，驱动着地质过程并提供必需的资源。在IB和WJEC科学课程中，你需要理解矿物的性质、岩石的分类、岩石循环以及如何鉴定常见的标本。这份复习指南将核心概念一一拆解，为你提供清晰讲解和聚焦考试的见解，同时适用于两个课程体系。
1. Introduction to Minerals | 矿物简介
A mineral is a naturally occurring, inorganic solid with a definite chemical composition and an ordered internal crystal structure. Examples include quartz (SiO₂), calcite (CaCO₃), and halite (NaCl). Minerals are the building blocks of rocks, and each mineral has a unique set of physical and chemical properties that allow us to identify it.
矿物是天然形成的、无机固体，具有确定的化学成分和有序的内部晶体结构。例如石英（SiO₂）、方解石（CaCO₃）和石盐（NaCl）。矿物是构成岩石的基本单元，每种矿物都有一套独特的物理和化学性质，使我们能够对其进行鉴定。
Key points: Minerals must be naturally occurring – synthetic gemstones like cubic zirconia are not considered true minerals. They must also be crystalline, meaning atoms are arranged in a repeating pattern. Amorphous substances such as volcanic glass (obsidian) are mineraloids rather than minerals.
要点：矿物必须是天然形成的——合成立方氧化锆等人造宝石不被视为真正的矿物。它们还必须具有晶体结构，即原子以重复的模式排列。非晶质物质如火山玻璃（黑曜岩）属于似矿物，而非真正的矿物。
2. Physical Properties of Minerals | 矿物的物理性质
We use several observable properties to identify minerals in the field and laboratory. The most important are colour, streak, lustre, hardness, cleavage, fracture, and specific gravity. These properties arise directly from the mineral’s composition and crystal structure, and they form the basis for practical identification tasks in exams.
我们在野外和实验室中使用多种可观察的性质来鉴定矿物。最重要的包括颜色、条痕、光泽、硬度、解理、断口和比重。这些性质直接源于矿物的成分和晶体结构，是考试中实际鉴别题的基础。
Hardness is measured on Mohs scale from 1 (talc) to 10 (diamond). A mineral can scratch any mineral with a lower number. Streak is the colour of the powder produced when a mineral is rubbed against a porcelain plate, and it is often more consistent than the surface colour.
硬度用莫氏硬度计测量，从1（滑石）到10（金刚石）。一个矿物可以刻划任何硬度更低的矿物。条痕是将矿物在无釉瓷板上摩擦时产生的粉末颜色，它通常比表面颜色更稳定。
| Mohs Hardness | Reference Mineral | Common Test |
|---|---|---|
| 1 | Talc | Easily scratched by fingernail |
| 2 | Gypsum | Can be scratched by fingernail |
| 3 | Calcite | Scratched by a copper coin |
| 4 | Fluorite | Easily scratched by a steel knife |
| 5 | Apatite | Scratched by a steel knife |
| 6 | Orthoclase Feldspar | Scratches glass with difficulty |
| 7 | Quartz | Easily scratches glass |
| 8 | Topaz | Scratches quartz |
| 9 | Corundum | Scratches topaz |
| 10 | Diamond | Hardest known mineral |
Lustre describes how light reflects from the surface: metallic, vitreous (glassy), pearly, silky, or dull. Cleavage is the tendency of a mineral to break along smooth planes related to its crystal lattice. Minerals like mica have one perfect cleavage plane, while halite has three directions at right angles. If a mineral breaks with irregular surfaces, it exhibits fracture.
光泽描述光如何从表面反射：金属光泽、玻璃光泽、珍珠光泽、丝绢光泽或暗淡光泽。解理是矿物沿与其晶格相关的平滑平面破裂的倾向。如云母有一个完美的解理面，而石盐有三个相互直交的解理方向。如果矿物破裂产生不规则表面，则显示断口。
3. Mineral Identification Tests | 矿物鉴定测试
Simple chemical and physical tests help distinguish minerals. The acid test uses dilute hydrochloric acid (HCl): calcite and other carbonates effervesce (fizz) as carbon dioxide gas is released. The reaction for calcite is shown below.
简单的化学和物理测试有助于区分矿物。酸测试使用稀盐酸（HCl）：方解石和其他碳酸盐会起泡（冒泡），释放出二氧化碳气体。方解石的反应如下所示。
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
Minerals like magnetite are magnetic, while haematite is only weakly magnetic. Some minerals, such as calcite, exhibit double refraction – objects viewed through a clear crystal appear doubled. The streak test is especially useful for metallic minerals: haematite gives a red-brown streak; pyrite (fool’s gold) gives a greenish-black streak, distinguishing it from real gold which has a yellow streak.
像磁铁矿这样的矿物具有磁性，而赤铁矿磁性很弱。有些矿物如方解石表现出双折射——透过透明晶体看到的物体会出现重影。条痕测试对于金属矿物特别有用：赤铁矿产生红褐色条痕；黄铁矿（愚人金）产生绿黑色条痕，这将其与真正的黄金区分开来，黄金的条痕为黄色。
Specific gravity (relative density) can be felt by hand or measured in the lab. Galena (PbS) feels heavy for its size. Examiners may ask you to suggest identification tests for unknown minerals based on their properties.
比重（相对密度）可以手工掂量或在实验室测量。方铅矿（PbS）在相同体积下感觉沉甸甸的。考官可能会让你根据矿物的性质提出鉴定未知矿物的测试方法。
4. Introduction to Rocks and the Rock Cycle | 岩石与岩石循环简介
A rock is a naturally occurring solid aggregate of one or more minerals or mineraloids. Rocks are classified into three major groups based on how they form: igneous, sedimentary, and metamorphic. The rock cycle describes the dynamic transitions between these rock types through processes such as melting, cooling, weathering, erosion, deposition, compaction, cementation, and metamorphism.
岩石是由一种或多种矿物或似矿物组成的天然固体集合体。根据形成方式，岩石可分为三大类：火成岩、沉积岩和变质岩。岩石循环描述了这些岩石类型之间通过熔化、冷却、风化、侵蚀、沉积、压实、胶结和变质等过程发生的动态转变。
The rock cycle is driven by Earth’s internal heat and external energy from the Sun. Uplift, burial, and plate tectonics recycle rocks over millions of years. In exams, you may be asked to sketch the cycle or explain how a specific rock transforms into another.
岩石循环由地球内部热量和来自太阳的外部能量驱动。隆起、埋藏和板块构造在数百万年间循环再造岩石。考试中，你可能需要绘制该循环的简图，或解释某一特定岩石如何转变为另一种。
5. Igneous Rocks: Formation and Types | 火成岩：形成与类型
Igneous rocks form from the cooling and solidification of magma (below surface) or lava (on the surface). They are classified by their texture and mineral composition. Intrusive (plutonic) igneous rocks cool slowly underground, allowing large crystals to grow, giving a coarse-grained texture. Granite is the most common intrusive rock, containing quartz, feldspar, and mica.
火成岩由岩浆（地下）或熔岩（地表）冷却固结形成。它们按结构和矿物成分分类。侵入岩（深成岩）在地下缓慢冷却，使大晶体得以生长，形成粗粒结构。花岗岩是最常见的侵入岩，含有石英、长石和云母。
Extrusive (volcanic) igneous rocks cool rapidly at the surface, resulting in fine‑grained or glassy textures. Basalt is a dark‑coloured, fine‑grained extrusive rock rich in iron and magnesium. Obsidian is a volcanic glass that cools so fast that no crystals form. Vesicular textures, like those in pumice, are created by trapped gas bubbles.
喷出岩（火山岩）在地表快速冷却，形成细粒或玻璃质结构。玄武岩是一种富含铁和镁的深色细粒喷出岩。黑曜岩是一种火山玻璃，冷却极快以至于没有晶体形成。气孔状结构，如浮岩中的，是由被困气泡造成的。
Cooling rate determines crystal size: slow cooling → large crystals; fast cooling → small or no crystals. This is a classic exam concept often tested with diagrams of interlocking textures.
冷却速度决定晶体大小：缓慢冷却 → 大晶体；快速冷却 → 小晶体或无晶体。这是一个经典的考试概念，常结合嵌合结构图进行考查。
6. Sedimentary Rocks: Formation and Features | 沉积岩：形成与特征
Sedimentary rocks form from sediments that are weathered, eroded, transported, deposited, and then lithified. Lithification involves compaction and cementation, where minerals like silica or calcite precipitate from groundwater and bind grains together. Common sedimentary rocks include sandstone, limestone, and shale.
沉积岩由经过风化、侵蚀、搬运、沉积然后成岩作用的沉积物形成。成岩作用包括压实和胶结，地下水中的二氧化硅或方解石等矿物沉淀并将颗粒粘结在一起。常见的沉积岩包括砂岩、石灰岩和页岩。
Sandstone is composed mainly of sand‑sized quartz grains and feels gritty. Limestone is predominantly made of calcite, often formed from marine organisms’ shells and skeletons. Chalk is a soft, white limestone. Shale and mudstone form from fine clay and silt particles, often in calm water, and they may split easily along bedding planes.
砂岩主要由砂粒大小的石英颗粒组成，摸起来粗糙有砂感。石灰岩主要由方解石构成，通常来源于海洋生物的壳和骨骼。白垩是一种软而白的石灰岩。页岩和泥岩由细粒的粘土和粉砂颗粒在静水中形成，它们易沿层面裂开。
Fossils are exclusively found in sedimentary rocks, as the heat and pressure of metamorphism or the melting of igneous processes destroy organic remains. Ripple marks, mud cracks, and graded bedding are sedimentary structures that reveal past environments.
化石仅存在于沉积岩中，因为变质作用的热和压力或火成过程的熔化会破坏有机遗骸。波痕、泥裂和递变层理等沉积构造揭示了过去的沉积环境。
7. Metamorphic Rocks: Changes and Textures | 变质岩：变化与结构
Metamorphic rocks form when existing rocks are subjected to high temperature and pressure, causing mineralogical and textural changes without melting. Regional metamorphism occurs over large areas due to tectonic forces, producing foliated rocks with aligned minerals. Schist and gneiss are examples of high‑grade foliated rocks.
变质岩是原岩在高温高压下发生矿物成分和结构变化形成的，整个过程不经历熔化。区域变质作用由构造力在大范围区域内发生，产生具有定向排列矿物的片理状岩石。片岩和片麻岩是高级别片理状岩石的例子。
Contact (thermal) metamorphism happens when rocks are heated by nearby magma. The resulting rock is typically non‑foliated, like marble (from limestone) and quartzite (from sandstone). Marble is prized for sculpture, while slate – a low‑grade foliated rock from shale – is used for roofing.
接触（热）变质作用发生在岩浆侵入围岩时。产生的岩石通常无片理，如大理岩（由石灰岩变质而成）和石英岩（由砂岩变质而成）。大理岩深受雕刻青睐，而板岩——由页岩经低级变质形成的片理状岩石——常用于屋顶。
Key metamorphic changes: limestone → marble; shale → slate → phyllite → schist → gneiss; sandstone → quartzite. Memorising these progressions can help answer sequence questions.
关键变质转化：石灰岩 → 大理岩；页岩 → 板岩 → 千枚岩 → 片岩 → 片麻岩；砂岩 → 石英岩。记住这些演变顺序有助于解答序列题。
8. Weathering and Erosion | 风化与侵蚀
Weathering is the in‑situ breakdown of rocks at the Earth’s surface. Physical weathering includes freeze‑thaw action, where water enters cracks, freezes and expands, eventually breaking the rock. Exfoliation (onion‑skin weathering) occurs due to pressure release. Chemical weathering involves reactions that alter minerals, such as hydrolysis of feldspar to clay minerals.
风化是岩石在地表原地发生的分解作用。物理风化包括冻融作用：水进入裂缝，结冰时体积膨胀，最终使岩石破裂。层裂（洋葱状风化）是由于压力释放而产生。化学风化涉及改变矿物的化学反应，例如长石水解形成粘土矿物。
Carbonation is a crucial chemical weathering process for limestone landscapes. Rainwater containing dissolved carbon dioxide forms weak carbonic acid (H₂CO₃), which reacts with calcium carbonate to form soluble calcium hydrogencarbonate. This leads to karst features like caves, stalactites, and sinkholes.
碳酸化作用是石灰岩地貌中一项关键化学风化过程。含有溶解二氧化碳的雨水形成弱碳酸（H₂CO₃），它与碳酸钙反应生成可溶的碳酸氢钙。这导致喀斯特地貌，如洞穴、钟乳石和落水洞。
CaCO₃ + H₂CO₃ ⇌ Ca(HCO₃)₂
Erosion is the removal and transport of weathered material by water, wind, ice, or gravity. Both weathering and erosion drive the sediment supply for sedimentary rocks and shape landscapes.
侵蚀是指风化产物被水、风、冰或重力移除并搬运的过程。风化与侵蚀共同为沉积岩提供物质来源，并塑造地貌景观。
9. Fossils and Geological Time | 化石与地质年代
Fossils are the preserved remains or traces of ancient organisms. They form when an organism is rapidly buried by sediment, preventing decay. Hard parts such as shells and bones are more likely to fossilise. Mould and cast fossils, carbon films, and trace fossils (tracks, burrows) are common types.
化石是古生物保存下来的遗骸或遗迹。它们形成于生物体被沉积物迅速掩埋、防止腐烂的条件下。壳和骨骼等坚硬部分更易形成化石。印模化石与铸模化石、碳膜化石以及遗迹化石（足迹、潜穴）都是常见类型。
The geological time scale divides Earth’s 4.6‑billion‑year history into eons, eras, periods, and epochs. The Phanerozoic Eon includes the Palaeozoic, Mesozoic, and Cenozoic Eras. Major extinction events and the first appearance of certain fossils help define boundaries. The end‑Cretaceous extinction wiped out dinosaurs and is marked by an iridium‑rich clay layer.
地质年代表将地球46亿年历史划分为宙、代、纪、世。显生宙包括古生代、中生代和新生代。大灭绝事件和特定化石的首次出现有助于界定年代边界。白垩纪末灭绝使恐龙消失，并以富含铱的粘土层为标志。
Index fossils, such as ammonites and trilobites, were widespread, abundant, and lived for a short geological time – making them valuable for correlating rock layers in different locations.
标准化石，如菊石和三叶虫，分布广泛、数量丰富且存在的地质时间短暂，因此它们对对比不同地点的岩层很有价值。
10. Resources from Rocks and Minerals | 来自岩石与矿物的资源
Rocks and minerals are vital natural resources. Mineral ores such as haematite (Fe₂O₃) and bauxite (Al₂O₃) are mined for iron and aluminium. Limestone is quarried for cement and as a building stone. Granite is used for countertops and monuments due to its durability. Clay minerals are essential for brick and pottery production.
岩石和矿物是重要的自然资源。赤铁矿（Fe₂O₃）和铝土矿（Al₂O₃）等矿石被开采以提取铁和铝。石灰岩被开采用于制造水泥并用作建筑石材。花岗岩因其耐久性而用于台面和纪念碑。粘土矿物是制砖和陶器的关键原料。
Fossil fuels – coal, oil, and natural gas – are formed from ancient organic matter, not minerals, because they are not inorganic and crystalline. In IB WJEC contexts, you need to distinguish between mineral resources and energy resources.
化石燃料——煤、石油和天然气——由古代有机质形成，而不是矿物，因为它们不是无机结晶物质。在IB和WJEC的课程背景下，你需要区分矿产资源与能源资源。
Sustainable extraction and the environmental impact of quarrying and mining, such as habitat destruction, dust, and water pollution, are often highlighted in exam essays.
可持续开采以及采石和采矿的环境影响，如栖息地破坏、粉尘和水污染，常在考试论述题中被重点提及。
11. Common Rock Examples Detailed | 常见岩石详解
Granite is a light‑coloured, coarse‑grained intrusive igneous rock composed of quartz, feldspar, and mica. Its interlocking crystals give it strength, and it is widely used in construction. In the landscape, granite forms tors and upland areas due to its resistance to erosion, but it is susceptible to chemical weathering of feldspar.
花岗岩是一种浅色、粗粒的侵入火成岩，由石英、长石和云母组成。其交错的晶体赋予它强度，广泛用于建筑。在地貌上，花岗岩因其抗侵蚀力而形成突岩和高地，但它的长石易受化学风化。
Limestone (sedimentary) mainly consists of calcite. It fizzes with dilute acid and often contains fossils. Limestone pavements with clints and grikes are classic karst features. In the UK, the Yorkshire Dales showcase extensive Carboniferous Limestone scenery.
石灰岩（沉积岩）主要由方解石构成。它遇稀酸起泡，常含有化石。具有岩沟和石芽的石灰岩路面是经典的喀斯特地貌。在英国，约克郡谷地展示了广阔的石炭纪石灰岩景观。
Marble (metamorphic) forms from limestone or dolomite. It is non‑foliated, with interlocking calcite crystals that give it a sugary texture and the ability to take a high polish. Unlike limestone, marble does not usually contain fossils, because the metamorphic process destroys them.
大理岩（变质岩）由石灰岩或白云岩变质形成。它是无片理的，交错的方解石晶体赋予它糖粒状质地，并可高度磨光。与石灰岩不同，大理岩通常不含化石，因为变质过程破坏了化石。
12. Exam Tips and Common Misconceptions | 考试技巧与常见误区
Many students confuse rocks with minerals. Remember: minerals are homogeneous substances with specific formulas; rocks are mixtures of minerals. When asked ‘Name the rock this mineral is likely found in,’ relate it to texture and composition. Quartz and feldspar → granite; calcite → limestone or marble.
许多学生混淆了岩石和矿物。记住：矿物是具有特定化学式的均质物质；岩石是矿物的混合物。当被问到“这种矿物可能存在于哪种岩石中”时，要联系结构和成分进行回答。石英和长石 → 花岗岩；方解石 → 石灰岩或大理岩。
Beware of oversimplifying crystal size vs. cooling rate: a porphyritic texture (large crystals in a fine matrix) indicates two‑stage cooling – slow then fast. Always link texture to the cooling history. For metamorphic rocks, foliation results from directed pressure; lack of foliation usually indicates uniform pressure or lack of platy minerals.
要注意不要过度简化晶体大小与冷却速率的关系：斑状结构（细粒基质中有大晶体）说明经历了两阶段冷却——先慢后快。永远要将结构与冷却历史联系起来。对于变质岩，片理源于定向压力；无片理通常指示压力均匀或缺乏片状矿物。
When writing equations for chemical weathering, state the full balanced equation. The reaction of limestone with carbonic acid is reversible, leading to the deposition of stalactites and stalagmites in caves. This is a favourite application question.
在写风化化学方程式时，要写出完整的配平方程式。石灰岩与碳酸的反应是可逆的，导致洞穴中钟乳石和石笋的沉积。这是常见的应用型考题。
Finally, always use precise terminology: ‘clastic’ vs. ‘crystalline,’ ‘foliated’ vs. ‘non‑foliated,’ ‘intrusive’ vs. ‘extrusive.’ Label diagrams with exact rock names and key identifiers. Practice interpreting geological cross‑sections and explaining the sequence of events using the principle of superposition and cross‑cutting relationships.
最后，永远使用精确术语：“碎屑状”与“结晶状”，“片理状”与“非片理状”，“侵入”与“喷出”。给图表标上准确的岩石名称和关键识别特征。练习解读地质剖面图，并运用叠置原理和穿插关系解释事件的顺序。
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