chapter 3 geo

. explain the relationship between graphite and diamond and the environments on which these minerals are formed.

(A) covalent bonds form when adjacent carbon atoms share electrons. (B) in a diamond, covalently bonded carbon atoms form a strong three-dimensional structure. (C) in graphite sheets of covalently bonded carbon atoms are linked by weaker van deer waals forces. The more tightly packed structure of diamond is related to its formation at depths greater than 150km below earth's surface. Whereas the more open structure of graphite is consistent with its formation in the shallow crust.

Molecule

A stable combination of two or more atoms linked together by chemical bonds; the smallest part of a compound that retains the properties of the compound and can participate in a chemical reaction.

Element

A substance that cannot be broken down using chemical methods. All atoms of an element have the same number of protons.

Compound

A substance that contains two or more different chemical elements that are joined by bonds and can be separated into simpler substances by chemical reactions; a molecule is the smallest particle of a compound.

Organic

A substance that was part of a living organism; contains carbon-hydrogen bonds.

Fracture

A surface along which rupture occurs in a rock near earth's surface; a mineral possesses a fracture when it breaks along irregular surfaces rather than cleavage planes

Native metal

A type of ore mineral made up of single metallic element.

Non-ferromagnesian silicate

A type of silicate mineral that does not contain iron or magnesium.

Minerals are inorganic

Do not include hydrocarbons (C,H,0) Generally do not include compounds that make up living organisims Include some substances that are produced by living things but are not hydrocarbons (e.g., calcite)

Habit

A minerals characteristic outward appearance.

Anion

A negatively charged ion.

Electron

A negatively-charged subatomic particle with almost no mass; electrons orbit the nucleus of an atom.

Muscovite

A non-ferromagnsian sheet silicate that incorporates aluminum and water into its crystal structure; the sheet like arrangement of silicate tetrahedra results In a strong cleavage

Evaporate mineral

A nonsilicate rock-forming miner produced by the evaporation of saltwater; often the product of the evaporation of ancient seas.

Hardness'

Moh's hardness scale

Cation

A positively charged ion.

Clay mineral

A rock-forming mineral with a sheet-like silicate structure; commonly formed by the breakdown of feldspar during weathering.

Mica group

A set of minerals made up of sheets of silicate tetrahedral connected to one another by cations.

Quartz

A silicate mineral made up almost entirely of silicon and oxygen.

Mineraloid

A solid material that differs from mineral because it lacks regular atomic structure and its therefore not crystalline.

• Covalent bond:

carbon atoms share electrons forming strong covalent bonds in the mineral diamond.

Covalent bond

A bond created when two or more atoms share electrons

Amphibole group

A medium-grade nonfoliated metamorphic rock for which the parent rock is mafic.

Ore mineral

A mineral from which a metal can be economically extracted; typically a metal sulfide or oxide.

fracture

-absence of cleavage irregular fracture conchoidal fracture density -specific gravity chemical reactivity -calcity effervesces with HCL

Carbonate mineral

A mineral in which common cations such as calcium and magnesium are bonded to a combination of carbon and oxygen to form minerals such as calcite and dolomite; the most common nonsilicate.

Nonsilicate minerals

A mineral that does not contain silicon, such as calcite

• Covalent Bonds

: atoms share electrons ( bonds are the result of this sharing)

Silicate tetrahedron

A building block of a silicate mineral consisting of a central silicon cation bonded with four negatively charged oxygen anions positioned at the corners of the block.

Ionic bond

A chemical bond that results from the transfer of an electron from one atom to another.

Chemical formula

A description of a mineral that lists its component ions according to the proportion in which they occur in the mineral.

Pyroxene group

A group of calcium-magnesium-iron silicates that are usually green, brown, black in color.

Garnet group

A group of minerals with an isolated silicate structure like that of the olivine group, but with different compositions; occurs most commonly in metamorphic rocks

Ion

An atom that has an electric charge because of an imbalance in the number of protons and electrons.

Nucleus

An atom's dense central unit, which contains protons and (with the exception of hydrogen) neutrons and is orbited by electrons.

EXPLAIN why quartz occurs in various colors.

As Quartz grows, it commonly encounters and absorbs impurities that can result in a wide variety of colors including grey, pink and purple.

Minerals have a specific structure

Atoms and molecules arranged in a specific way

Minerals are crystalline solids

Atoms and molecules arranged in an orderly, three-dimensional, repeating pattern, forming crystals Polymorphs have the same formula but different crystal structure and are therefore different minerals.

Minerals have a specific chemical composition

Can be described by a specific chemical formal (e.g. Fe2 O3)

Ferromagnesian silicate

Category of silicate minerals that contains significant amounts of iron and magnesium.

Types of rocks don't have minerals

Coal Obsidian

Inorganic

Compounds that lack carbon derived from living matter.

gems

Crystals that have intrinsic value because of their beauty, durability, rarity, or size.

Olivine group

Ferromagnesian silicate minerals characterized by isolated tetraherdra that are linked by iron and/or magnesium ions.

how do ionic, covalent, and metallic bonds differ in their use of electron mobility?

Ionic bonds: bonds between atoms are formed by electron transfer. Covalent bonds: electron sharing Metallic bonds: by the development of a common electron cloud.

More than 4500 minerals known

Less than 1% are common in earth's crust: rock forming minerals

explain the differences in the cleavage patterns of pyroxenes, amphiboles, and micas.

Micas consist of long sheets of silicate structure. No obvious signs of cleavage and instead display conchoidal surfaces. Pyroxenes & amphiboles: pyroxene forms a single chain whereas amphibole forms double chains, implying the shape of their chains also differs. For both mineral groups, the bonds between the silicate chains are week and so control the orientation of their respective cleavages. Because of differencesin the shape of their chains the angle between their respective cleavages is different 90 for pyroxene and 60 to 120 for amphiboles. The difference between them is most visible on their top faces.

Minerals are a

Minerals are a naturally occurring on earth and other planetary bodies. Do not include solids that are formed in a lab.

why do minerals have specific chemical formulas whereas rocks do not?

Minerals are inorganic solids with crystalline structures and characteristic psychical properties that are determined by the regular internal arrangement of their constituent atoms. A rock on the other hand is aggregated of one or more minerals or mineralogist. ( recall the mineraloids are solid materials that lack a regular atomic structure and are there fore not crystalline).

Silicate mineral

Minerals in which a variety of cations are bonded with silicon and oxygen.

Rock-forming mineral

Minerals that are common in rocks.

Polymorph

Minerals with the same chemical compostion but with different crystal structures.

Neutron

One of the particles in an atom's nucleus ( a proton is the other); aneutron carries no charge and has approximately the same mass as a proton.

Luster

Refers to the way in which mineral reflects light.

Two main categories of rock forming minerals

Silicates (most) Contain Si and O Nonsilicates (some) Do not contain Si and O

Diaphaneity

Some unusual properties -striations magnetism, taste, double refraction

explain the relationship between metallic bonding and the characteristics properties of metals. How can these properties of aid in mineral exploration?

The atoms become positive ions and the strength of the metallic bonds is related to the attraction between the positive layer of ions and the negative clouds of electrons. The electrons within the clouds in bonded metals move freely and can carry energy from one end of a piece of metal to the other which is why is metals are generally excellent condors of heat and electricity.

Mineral

The building block of rocks; a naturally occurring inorganic crystalline solid. The internal structure is an orderly arrangement of atoms, ions, or molecules.

Streak

The color of the mineral in powered form.

cleavage is not the same as

crystal structure

Feldspar group

The most abundant non-ferromagnesian silicate minerals in earth's crust.

Atomic number

The number of protons in an atom of an element.

Crystal face

The outer surface of a crystal with straight edges and sharp corners

Crystal

The perfect regular geometric shape of a mineral.

Proton

The positively-charged particle in an atoms nucleus; the number of protons determines the atomic number of an element.

Specific gravity

The ratio mass of an object relative to the mass of an equal volume of water at 4c.

Atom

The smallest unit of an element that displays all the physical and chemical properties of that element.

Crystal from crystal structure

The stable orderly arrangement of ions within a crystal

Cleavage color

The tendency of a mineral to break (or "CLEAVE") along preferred directions; reflects systematic weaknesses in the internal structure of a mineral in the directions of their weakest bonds.

Metallic bond

When atoms combine to form a piece of metal each atom gives up an outer electron. Collectively, the atoms form a layer of positive ions, with a freely moving, common cloud of shared electrons swarming around them; the strength of a metal is directly related to the strength of its metallic bonds.

• Structure of atoms:

an atom consist of a nucleus composed of protons and neutrons. Surrounding the nucleus are electrons.

• Van der waals forces:

atoms and molecules can have a weak charged or imbalance of charge ( charge result in weak attractive forces between atoms and molecules)

Atoms that form minerals are held together

by chemical bonds and intermolecular forces.

• Ionic bonds

electrons are transferred from one atom to another (bond are the result of the attractive forces between positively and negatively charged ions)

Metallic bonds:

electrons move freely from atom to atom (bonds are the result of attraction between positively charged metal ions and negatively charged electrons)

crystal form

law constancy of interfacial angle ("Steno's Law)

Structure of silicate minerals:

silicate minerals can be classified based on the arrangement of silica tetrahedra.

example of ionic bonding

• Ionic bonding: an electron is transferred from a sodium ion atom to a chlorine atom. The positively charged sodium ion and negatively charged chlorine ion attract each other to form the mineral halite

Metallic bonding :

• Metallic bonding : outer electrons are shared by atoms in the mineral gold.

Elements (the building blocks of Minerals)

• Minerals are composed of elements. • Elements are the fundamental substances that make up all matter. • Minerals are made of single elements or of compounds.

Minerals

• Most rocks are made of one or more types of minerals • Most materials that people use are derived either from minerals or from organic matter

Minerals By definition

• Naturally occurring • Inorganic • Crystalline • Specific chemical composition • Define chemical structure

Van der Waals forces:

• Van der Waals forces: sheets of covalently bonded carbon atoms are held together by weak van der Waals forces in the mineral graphite.

cleavage

• quality • number of directs • one e.g. mica • two at right angles- e.g. feldspar, proxene • two not at right angle- e.g. amphibole • three at at right angles (cubic) e.g. Halite• three not at right angle (rhombohedral) - e.g. calcite • four or six not common