Basic Geology Concepts

The definition of a mineral

A mineral is a naturally occurring, inorganic solid with a definite chemical composition

and an orderly arrangement of atoms.

Mineral Characteristics

1. All minerals are formed by natural processes.

2. Minerals are inorganic.

3. Every mineral is an element or compound with a definite chemical composition.

4. Minerals are crystalline solids.

The definition of a crystal

A crystal is a solid in which the atoms are arranged in orderly, repeating patterns.

晶体和矿物的相同点和不同点

地球科学中，只需要知道晶体强调内部有序而重复的结构，矿物除需满足此条件之外，

还需要满足自然产生、是无机物这两个条件。知道这些就足够了。

矿物的来源

1. 岩浆冷却时形成；

2. 溶液饱和溶质析出而形成（岩盐）；

岩石和矿物的关系

岩石往往是多种矿物的组合体；

矿物是化学成分相对单一的物质，接近纯净物；所以，岩石一般是混合物。

地壳的八大成岩矿物

1. Quartz 石英

2. Feldspar 长石

3. Mica 云母

4. Pyroxene 辉石

5. Amphibole 闪石

6. Olivine 橄榄石

7. Garnet 石榴石

8. Calcite 方解石

地壳的八大组成元素：

养闺女贴给哪家没：O, Si, Al, Fe, Ca, Na, K, Mg, Other

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矿物判别方式

最初级的矿物判别方式：Color and appearance are two obvious clues that can

be used to identify minerals.

Hardness：A measure of how easily a mineral can be scratched is its hardness.

Luster： The way a mineral reflects light is known as luster. 【There are two

types of luster — metallic luster and nonmetallic luster. Describing the luster of

nonmetallic minerals is a subjective process. Using luster to identify a mineral

should usually be used in combination with other physical characteristics.】

Specific Gravity： The specific gravity of a mineral is the ratio of its weight

compared with the weight of an equal volume of water.

Streak：Streak is the color of a mineral when it is broken up and powdered.

也就是说，Streak 是矿物在素瓷上划过后留下的条纹的颜色，这与矿物变成粉

末后的颜色相同。【The streak test works only for minerals that are softer than

the streak plate.】

Cleavage(解理) and fracture：A mineral that splits relatively easily and evenly

along one or more flat planes is said to have cleavage. Minerals that break with

rough or jagged edges are said to have fracture. cleavage 指的就是矿物平整而

容易形成的断裂面；相反，fracture 指的是矿物不平整的断裂面。一种矿物只能有

cleavage 或 fracture。Cleavage 形成的条件：Minerals break along planes

where atomic bonding is weak.

In conclusion, the most reliable way to identify a mineral is by using a

combination of several tests of its physical properties.

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Tetrahedron [晶体的]四面体: In many silicates, one silicon atom bonds with four

oxygen ions to form a tetrahedron.

Mineral Groups 矿物组

The 1st mineral group——Silicates 硅酸盐：Minerals that contain silicon and

oxygen, and usually one or more other elements, are known as silicates.【basic

building block of the silicates ——the silica tetrahedron 硅四面体】 （石棉

asbestos 石棉是天然的纤维状的硅酸盐类矿物质的总称。）

The 2nd mineral group——Carbonates 碳酸盐：Carbonates are minerals

composed of one or more metallic elements and the carbonate ion(碳酸盐离子

) .

The 3rd mineral group——Oxides 氧化类矿物：Oxides are compounds of

oxygen and a metal.

Other major mineral groups are：

sulfides(硫化物): Sulfides (硫化物) are compounds of sulfur (硫) and one or more

elements.

sulfates(硫酸盐): Sulfates (硫酸盐)are composed of elements with the sulfate

ion( 硫酸根离子 )

halides(卤化物)：Halides (卤化物) are made up of chloride( Cl, 氯 ) or

fluoride( F, 氟 ) along with calcium( 钙 ), sodium( 钠 ), or potassium( 钾 ).

native elements(天然元素)：A native element (天然元素), such as silver (Ag)

or copper (Cu), is made up of one element only.

@硅酸盐---硅四面体

@碳酸盐---碳酸根+一种或多种金属元素

@硫酸盐---硫酸根+其他元素

@氧化类矿物---氧气+一种金属

@硫化物---硫+一种或多种元素

@卤化物---氯或氟+钙或纳或钾

@天然元素-由一个元素组成

Economic minerals 具有经济价值的矿物

Ore 矿石：A mineral is an ore if it contains a useful substance that can be mined at a

profit.

Gem 宝石：Gems are valuable minerals that are prized for their rarity and beauty.

Diamond 钻石

Ruby 红宝石

Sapphire 蓝宝石

Emerald 绿宝石

Amethyst 紫水晶

The definition of a rock:

A rock is a mixture of minerals, rock fragments, volcanic glass, organic matter, or

other natural materials.

岩石循环：

Rock cycle 的发现者和提出者： James Hutton

Magma: Magma is molten rock below Earth’s surface.

Lava: Lava is magma that flows out onto Earth’s surface.

Where does the heat melting rock come from?

One source is the heat left over from the formation of the planet, which originally

was molten.

The other source but also the main source is the decay of radioactive

elements(放射性元素的衰变) within Earth.

火成岩的分类方式

1. 岩石形成方式 [Magma---Intrusive rocks ; Lava---extrusive rocks ]

1) Intrusive Rocks 侵入岩:Rocks that form from magma below the surface are

called intrusive igneous rocks. 侵入型岩浆岩在地表以下一定深度处形成，并

被其他岩石包围着，所以需要较长的时间才能冷却。缓慢冷却形成的侵入岩

的晶体颗粒较大，可用肉眼观察到。

2) Extrusive Rocks 喷出岩:Extrusive igneous rocks are formed as lava cools

on the surface of Earth. When lava flows on the surface, it is exposed to air

and water. Lava cools quickly under these conditions. 快速的冷却使得原子没

有足够的时间形成较大的矿物晶体。 Therefore, extrusive igneous rocks

are fine- grained( 细颗粒的 ).

2. 形成岩石的岩浆的化学成分

1) basaltic rock 玄武质岩:Basaltic igneous rocks are dense , dark-colored

rocks. Its dark color is given by Iron and magnesium in minerals. They form

from magma that is rich in iron and magnesium (Mg ) and poor in silica

(Si).

2) Granitic Rocks 花岗质火成岩:Granitic igneous rocks are light-colored

rocks of a lower density than basaltic rocks. Granitic magma is thick and

stiff and contains lots of silica but lesser amounts of iron and magnesium.

3) Andesitic Rocks 安山质火成岩:Andesitic igneous rocks have mineral

compositions between those of basaltic and granitic rocks.

The definition of the Metamorphic Rocks

Rocks that have changed because of changes in temperature and pressure or the

presence of hot, watery fluids are called metamorphic rocks.

Types of Metamorphism

The effects of metamorphism can be the result of contact metamorphism(接触变质),

regional metamorphism(区域变质), or hydrothermal metamorphism(热液变质).

Contact metamorphism 接触变质:

When molten material, such as that in an igneous intrusion( 岩 浆 入 侵 ), comes in

contact with solid rock, a local effect called contact metamorphism occurs.

Hydrothermal metamorphism 热液变质:

Hydrothermal metamorphism occurs, when very hot water reacts with rock and alters

its chemical and mineral composition.

Grades of Metamorphism 变质等级

Different combinations of temperature and pressure result in different grades of

metamorphism.

一种变质岩可有多种母岩(parent rocks) ，母岩可以是沉积岩、火成岩或者变质岩。

The definition of texture

Texture refers to the size, shape, and distribution of the crystals or grains that make

up a rock.

描述“texture”的词汇：

fine-grained 细颗粒的

coarse-grained 粗颗粒的

Classifying Metamorphic Rocks 变质岩分类（distribution）

Metamorphic rocks are classified into two textural groups: foliated( 页 理 状 ) and

nonfoliated(非页理状).

【页理状：Shale 页岩------变质作用------Slate 板岩（防水建筑材料）

非页理状：Sandstone 砂岩------变质作用------Quartzite 石英岩

limestone 石灰岩------变质作用------marble 大理石（雕塑建筑等）】

Sediment 沉积物

Sediments are loose materials such as rock fragments, mineral grains, and bits of

shell(贝壳) that have been moved by wind, water, ice, or gravity.

Sedimentary rock 沉积岩

Sedimentary rock forms when sediments are pressed and cemented together, or

when minerals form from solutions.

沉积岩的形成过程

Step1: Compaction 压实

Step2: Cementation 黏 结 ： Cementation occurs when mineral growth glues

sediment grains together into solid rock. （ Sediments are cemented together as

minerals crystallize between grains, e.g., CaCO3 or Fe2O3.）

Lithification 成岩过程：

Compaction + Cementation= Lithification

Lithification : the physical and chemical processes that transform sediments into

sedimentary rocks.

Classifying Sedimentary Rocks

Sedimentary rocks are usually classified as detrital, chemical, or organic, by their

composition and by the manner in which they formed.

1. Detrital Sedimentary Rocks 碎屑沉积岩——第一类沉积岩

Detrital sedimentary rocks are made from the broken fragments of other rocks.

【Conglomerate 砾岩 ---formed by round sediment

Breccia 角砾岩---formed by anglar sediment】

2. Chemical Sedimentary Rocks 化学沉积岩——第二类沉积岩

Chemical sedimentary rocks form when dissolved minerals come out of solution.

Chemical sedimentary rocks are different，because they are not made from pieces

of preexisting rocks.

【蒸发岩是一种沉积岩 但它不是由 sediment 聚集形成的 而是直接从自然界的矿物溶

液中 析出结晶而形成的】

3. Organic Sedimentary Rocks 生物沉积岩——第三类沉积岩

Rocks made of the remains of once-living things are called organic sedimentary

rocks.

One of the most common organic sedimentary rocks is fossil-rich limestone.

【Limestone 石灰岩：主要矿物成分：Calcite, 方解石 化学成分：Calcium carbonate

石灰岩形成地的古地理环境往往是浅海或湖泊。

贝类生物及珊瑚的“生物沉积”

石灰岩的主要化学成分 CaCO3 易被溶蚀，故在石灰岩地区多形成石林和溶洞，即喀斯

特地貌。 】

【粉笔，coal 也是 sedimentary rocks organic】

Fault

There is a limit to how far a wooden craft stick can bend. This is called its elastic

limit(弹性极限) .

Once the elastic limit is passed, the rocks may break. When rocks break, they move

along surfaces called faults.

Earthquake

An earthquake is usually the vibrations produced by the breaking of rocks near plate

boundaries(大陆板块边界).

Normal Faults 正断层：

Tensional forces( 张力 ) inside Earth cause rocks to be pulled apart, forming normal

faults.

判 断 方 法 ： Along a normal fault, rock above the fault surface moves downward in

relation to(相对于) rock below the fault surface.

Reverse Faults 逆断层：

Reverse faults result from compression forces(压力) that squeeze(压紧) rock.

判 断 方 法 ： Along a reverse fault, rock above the fault surface moves upward in

relation to rock below the fault surface.

Strike-Slip Faults 走滑断层：

At a strike-slip fault, rocks on either side of the fault are moving past each other

without much upward or downward movement.

Three types of seismic waves

Primary Waves( P-waves)

Secondary Waves(S-waves)

Surface Waves

Secondary Waves( S-waves) 横波 凹凸波

Secondary waves (S-waves) move through Earth by causing particles in rocks to

move at right angles to the direction of wave travel. （摆绳上传播的波）

Primary Waves(P-waves) 纵波

Primary waves (P-waves) cause particles in rocks to move back and forth in the

same direction that the wave is traveling. （弹簧）

Surface waves 地面波

A surface wave causes rock particles to move both up and down and from side to

side.

地面波往往破坏力最大，because they cause the most movement of the ground, and

take the longest time to pass.

波速：P最快，Surface wave最慢

Epicenter 震中：The earthquake epicenter is the point on Earth’s surface directly

above the earthquake focus(震源).

The focus of the earthquake 震源：

The point where the seismic waves originate is the focus of the earthquake.

The focus of an earthquake is the point of initial fault rupture.

“时间差” 即“距离震中的距离”

若已知 P波和 S波达到某地震测量站的时间差，就可以得出震中距离此地震测量点的

距离。

地震波的固液传播特征

P-wave 在固、液体中均能传播，但在液体中的波速会降低。

S-wave 在液体中会丧失传播能力。

整体来说，地震波在致密的固体中传播速度较快(例如莫霍面)，在液体中减速(软流层)

甚至消失(外地核)。

地球内部结构及地震波阴影区

Lithosphere 岩石圈

Lithosphere, rigid, rocky outer layer of the Earth, consisting of the crust and the solid

outermost layer of the upper mantle. It extends to a depth of about 60 mi (100 km). It

is broken into about a dozen separate, rigid blocks, or plates ( plate tectonics).

Asthenosphere 软流层

Asthenosphere, zone of the Earth's mantle lying beneath the lithosphere, believed to

be much hotter and more fluid than the lithosphere. The asthenosphere is thought to

extend from about 60 mi (100 km) to about 450 mi (700 km) below the Earth's

surface.

Mohorovicic discontinuity 莫霍(不连续)面

Moho, or Mohorovicic discontinuity, boundary between the Earth’s crust and its

mantle. The Moho lies at a depth of about 22 mi (35 km) below continents and about

4.5 mi (7 km) beneath the oceanic crust. Modern instruments have determined that

the velocity of seismic waves increases rapidly at this boundary.