📚 Rocks and Minerals: OCR Science Revision | 岩石与矿物：OCR 科学复习要点
Welcome to our comprehensive revision guide on rocks and minerals, tailored for OCR A-Level Science. Understanding the Earth’s solid materials is fundamental to geology and environmental science. This article walks you through the key concepts, from mineral identification to the rock cycle, ensuring you grasp what you need for exam success.
欢迎阅读我们为 OCR A-Level 科学量身打造的岩石与矿物复习指南。理解地球的固体材料是地质学和环境科学的基础。本文带你梳理关键概念，从矿物鉴定到岩石循环，助你掌握考试所需的全部要点。
1. What are Minerals? | 什么是矿物？
A mineral is a naturally occurring, inorganic solid with a definite chemical composition and an ordered atomic arrangement. This means it must be formed by natural processes, not by living organisms, and it must have a fixed crystal structure. Examples include quartz (SiO₂) and calcite (CaCO₃).
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原子排列。这意味着它必须由自然过程形成，而非来自生物体，并且必须具备固定的晶体结构。例如石英（SiO₂）和方解石（CaCO₃）。
To be classified as a mineral, a substance must satisfy five criteria: it must be naturally occurring, inorganic, solid, have a definite chemical composition, and possess a crystalline structure. Ice meets these criteria, but synthetic diamonds do not.
要归类为矿物，物质必须满足五个标准：天然形成、无机、固态、化学成分确定、具有晶体结构。冰符合这些标准，但人造钻石不符合。
2. Mineral Properties | 矿物性质
Minerals are identified by their physical properties, which reflect their internal structure. The most commonly tested properties include colour, streak, lustre, hardness, cleavage, and fracture. Hardness is measured on Mohs scale, ranging from 1 (talc) to 10 (diamond).
矿物可通过其物理性质进行鉴定，这些性质反映了其内部结构。最常见的考查性质包括颜色、条痕、光泽、硬度、解理和断口。硬度用莫氏硬度计测量，范围从1（滑石）到10（金刚石）。
- Colour – visible hue, often unreliable due to impurities. / 颜色 – 可见色调，常因杂质不可靠。
- Streak – colour of powder when scratched on a streak plate. / 条痕 – 在条痕板上刻划后粉末的颜色。
- Lustre – way light reflects from the surface (metallic, vitreous, pearly). / 光泽 – 光线从表面反射的方式（金属、玻璃、珍珠光泽）。
- Hardness – resistance to scratching, vital for field identification. / 硬度 – 抵抗刮擦的能力，野外鉴定至关重要。
- Cleavage – tendency to break along flat planes. / 解理 – 沿平面裂开的趋势。
- Fracture – irregular breakage, like conchoidal in quartz. / 断口 – 不规则断裂，如石英的贝壳状断口。
3. Common Rock-Forming Minerals | 常见造岩矿物
Only a few dozen minerals make up the bulk of Earth’s crust. The most abundant group is the silicates, based on the SiO₄⁴⁻ tetrahedron. Quartz, feldspar, and mica are typical examples. Feldspar alone accounts for over 50% of the crust.
只有几十种矿物构成了地壳的主体。最丰富的是以 SiO₄⁴⁻ 四面体为基础的硅酸盐类。石英、长石和云母是典型例子。仅长石就占地壳的 50% 以上。
| Mineral / 矿物 | Group / 类型 | Key Feature / 关键特征 |
|---|---|---|
| Quartz | Silicate | Hardness 7, no cleavage / 硬度7，无解理 |
| Feldspar | Silicate | Two cleavage planes at 90° / 两组相互垂直的解理 |
| Mica | Silicate | Perfect basal cleavage, thin sheets / 极完全底面解理，薄片 |
| Calcite | Carbonate | Reacts with dilute HCl / 遇稀盐酸起泡 |
| Olivine | Silicate | Green, granular, high temperature / 绿色粒状，高温矿物 |
4. Igneous Rocks: Formation and Types | 火成岩：形成与类型
Igneous rocks form from the cooling and solidification of magma or lava. They are classified based on texture (grain size) and mineral composition. Intrusive (plutonic) rocks like granite cool slowly underground, producing large crystals. Extrusive (volcanic) rocks like basalt cool quickly at the surface, yielding fine-grained textures.
火成岩由岩浆或熔岩冷却凝固形成。它们根据结构（颗粒大小）和矿物成分进行分类。侵入岩（深成岩）如花岗岩在地下缓慢冷却，产生大晶体。喷出岩（火山岩）如玄武岩在地表快速冷却，形成细粒结构。
Bowen’s Reaction Series explains the sequence of mineral crystallisation from magma. Minerals such as olivine and pyroxene crystallise at high temperatures, while quartz and feldspar form at lower temperatures. This concept helps interpret igneous rock histories.
鲍文反应系列解释了矿物从岩浆中结晶的顺序。橄榄石和辉石等矿物在高温下结晶，而石英和长石在较低温度下形成。这一概念有助于解读火成岩的历史。
5. Sedimentary Rocks: Processes and Examples | 沉积岩：过程与实例
Sedimentary rocks originate from the accumulation and lithification of sediments. The main processes include weathering, erosion, transport, deposition, compaction, and cementation. Common examples are sandstone, limestone, and shale. These rocks often contain fossils and provide clues about past environments.
沉积岩源于沉积物的堆积和成岩作用。主要过程包括风化、侵蚀、搬运、沉积、压实和胶结。常见例子有砂岩、石灰岩和页岩。这些岩石常含化石，能提供过去环境的线索。
Sedimentary rocks are grouped into clastic (formed from fragments), chemical (precipitated from solution), and organic (rich in biological material). For instance, sandstone is clastic; rock salt is chemical; chalk is organic limestone.
沉积岩分为碎屑岩（由碎屑形成）、化学岩（从溶液中沉淀）和有机岩（富含生物物质）。例如，砂岩是碎屑岩；岩盐是化学岩；白垩是有机石灰岩。
6. Metamorphic Rocks: Heat and Pressure | 变质岩：热与压力
Metamorphic rocks arise when existing rocks are transformed by high temperature, pressure, or chemically active fluids without melting. This can produce new minerals and textures. Regional metamorphism affects large areas during mountain building, while contact metamorphism occurs near igneous intrusions.
变质岩是原有岩石在高温、高压或化学活动流体作用下，未熔融而改造形成的。这会产生新矿物和新结构。区域变质作用于造山带的大范围区域，接触变质则发生在火成侵入体附近。
Foliated rocks like slate, schist, and gneiss show aligned mineral grains due to directed pressure. Non-foliated rocks like marble and quartzite lack this alignment. Index minerals such as garnet and kyanite indicate specific metamorphic grades.
板岩、片岩和片麻岩等叶理状岩石因定向压力而显示矿物定向排列。大理岩和石英岩等非叶理状岩石则没有这种排列。石榴石和蓝晶石等指示矿物标志着特定的变质等级。
7. The Rock Cycle | 岩石循环
The rock cycle illustrates how Earth’s three rock types are interrelated through geological processes. Magma cools into igneous rock, which can be weathered into sediment. Sediment lithifies into sedimentary rock, which under heat and pressure becomes metamorphic rock. Metamorphic rock can melt again into magma, completing the cycle.
岩石循环说明了地球三大岩类如何通过地质过程相互转化。岩浆冷却形成火成岩，火成岩风化变成沉积物。沉积物成岩形成沉积岩，在热和压力下再变为变质岩。变质岩又可熔融成岩浆，完成循环。
Igneous → Sediment → Sedimentary → Metamorphic → Magma → Igneous
火成岩 → 沉积物 → 沉积岩 → 变质岩 → 岩浆 → 火成岩
Tectonic settings drive this cycle. Subduction zones recycle crust into the mantle, while uplift exposes deep rocks to weathering. Understanding the rock cycle helps predict resource locations and interpret landscape evolution.
构造背景驱动着这一循环。俯冲带将地壳回收到地幔，而隆升使深部岩石暴露于风化作用。理解岩石循环有助于预测资源位置并解读地貌演化。
8. Weathering and Erosion | 风化与侵蚀
Weathering is the breakdown of rocks in situ by physical, chemical, or biological agents. Mechanical weathering includes freeze-thaw and exfoliation; chemical weathering involves reactions like hydrolysis and carbonation. Erosion is the removal and transport of weathered material by water, wind, ice, or gravity.
风化是岩石在原地的破坏，由物理、化学或生物因素引起。机械风化包括冻融作用和层裂作用；化学风化涉及水解和碳酸化等反应。侵蚀则是被风化物质由水、风、冰或重力进行的搬运。
These processes are essential for soil formation and sediment supply. For example, feldspar weathers through hydrolysis to form clay minerals, a key reaction in the carbon cycle. Rates depend on climate, rock type, and slope.
这些过程对土壤形成和沉积物供应至关重要。例如，长石通过水解作用风化成粘土矿物，这是碳循环中的关键反应。风化速率取决于气候、岩石类型和坡度。
9. Resources from Rocks and Minerals | 岩石与矿物资源
Rocks and minerals are the source of many essential materials: metals from ores, construction aggregates, and industrial minerals like gypsum and halite. Resource extraction must balance economic benefits with environmental impacts, including habitat loss and pollution. Sustainable management practices are increasingly important.
岩石和矿物是许多必需材料的来源：金属来自矿石，还有建筑骨料以及石膏和石盐等工业矿物。资源开采必须在经济效益与栖息地丧失、污染等环境影响之间取得平衡。可持续管理实践日益重要。
Placer deposits, formed by gravity separation in streams, yield gold and tin. Hydrothermal veins produce copper, lead, and zinc. Understanding the geology of deposits is fundamental for exploration and resource assessment.
砂矿由水流中的重力分选形成，产出金和锡。热液脉则产出铜、铅、锌。理解矿床地质是勘探和资源评价的基础。
10. Fieldwork and Identification | 实地考察与鉴定
Field skills are central to OCR assessments. You may be asked to describe rock samples, interpret outcrops, or use simple tests (hardness, acid test). Always record grain size, mineral composition, colour, structure (bedding, foliation, vesicles), and fossil content where present.
野外技能是 OCR 考查的核心。你可能需要描述岩石标本、解读露头，或使用简单测试（硬度、酸测试）。始终记录粒度、矿物成分、颜色、构造（层理、叶理、气孔）以及可能存在的化石。
A hand lens and streak plate are essential tools. When identifying igneous rocks, note crystal size (coarse = intrusive, fine = extrusive). For sedimentary rocks, look for rounded grains or layering. Metamorphic rocks often show preferred mineral alignment or folding.
手持放大镜和条痕板是必备工具。鉴定火成岩时，注意晶体大小（粗粒 = 侵入岩，细粒 = 喷出岩）。沉积岩要寻找圆状颗粒或层理。变质岩常显示矿物定向排列或褶皱。
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