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Embed code for: 5 Beginning of minerals
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These are the notes taken on 10/17-10/19.
What do you think a mineral is? (Give Examples)
Are minerals valuable?
Describe the mineral at your table.
Agenda: Mineral Basics
Characteristics of Minerals
mineral a natural, usually inorganic solid that has a characteristic chemical composition, an orderly internal structure, and a characteristic set of physical properties.
To be a mineral, a substance must have four characteristics:
it must be inorganic-it cannot be made of or by living things;
it must occur naturally-it cannot be man-made;
it must be a crystalline solid;
it must have a consistent chemical composition.
Characteristics of Minerals, continued
The diagram below shows the four characteristics of minerals.
Kinds of Minerals
The 20 most common minerals are called rock-forming minerals because they form the rocks that make up Earth’s crust.
Ten minerals make up 90% of Earth’s crust: quartz, orthoclase, plagioclase, muscovite, biotite, calcite, dolomite, halite, gypsum, and ferromagnesian minerals.
All minerals can be classified into two main groups-silicate minerals and nonsilicate minerals-based on their chemical compositions.
Kinds of Minerals, continued
silicate mineral a mineral that contains a combination of silicon and oxygen and that may also contain one or more metals
Common silicate minerals include quartz, feldspars, and ferromagnesian minerals, such as amphiboles, pyroxenes, and olivines.
Silicate minerals make up 96% of Earth’s crust. Quartz and feldspars alone make up more than 50% of the crust.
nonsilicate mineral a mineral that does not contain compounds of silicon and oxygen
Nonsilicate minerals comprise about 4% of Earth’s crust.
Nonsilicate minerals are organized into six major groups based on their chemical compositions:
carbonates, halides, native elements, oxides, sulfates, and sulfides.
(Foldable of nonsilicates using book)
Double check understanding
What compound of elements will you never find in a nonsilicate mineral?
Nonsilicate minerals never contain compounds of silicon bonded to oxygen.
Each type of mineral is characterized by a specific geometric arrangement of atoms, or its crystalline structure.
crystal a solid whose atoms, ions, or molecules are arranged in a regular, repeating pattern.
One way that scientists study the structure of crystals is by using X rays. X rays that pass through a crystal and strike a photographic plate produce an image that shows the geometric arrangement of the atoms that make up the crystal.
Crystalline Structure of Silicate Minerals
silicon-oxygen tetrahedron the basic unit of the structure of silicate minerals; a silicon ion chemically bonded to and surrounded by four oxygen ions
Isolated Tetrahedral Silicates
In minerals that have isolated tetrahedra, only atoms other than silicon and oxygen atoms like silicon-oxygen tetrahedra together.
Olivine is an isolated tetrahedral silicate.
Crystalline Structure of Silicate Minerals, continued
What is the building block of the silicate crystalline structure?
The building block of the silicate crystalline structure is a four-sided structure known as the silicon-oxygen tetrahedron, which is one silicon atom surrounded by four oxygen atoms.
Ring silicates form when shared oxygen atoms join the tetrahedra to form three-, four-, or six-sided rings.
Beryl and tourmaline are ring silicates.
In single-chain silicates, each tetrahedron is bonded to two others by shared oxygen atoms.
Most single-chain silicates are called pyroxenes.
In double-chain silicates, two single chains of tetrahedra bond to each other.
Most double-chain silicates are called amphiboles.
In the sheet silicates, each tetrahedron shares three oxygen atoms with other tetrahedra. The fourth oxygen atom bonds with an atom of aluminum or magnesium, which joins the sheets together.
The mica minerals, such as muscovite and biotite, are sheet silicates.
In the framework silicates, each tetrahedron is bonded to four neighboring tetrahedra to form a three-dimensional network.
Frameworks that contain only silicon-oxygen tetrahedra are the mineral quartz.
Other framework silicates contain some tetrahedra in which atoms of aluminum or other metals substitute for some of the silicon atoms.
Quartz and feldspars are framework silicates.
The diagram below shows the tetrahedral arrangement of framework silicate minerals.
Crystalline Structure of Nonsilicate Minerals
Because nonsilicate minerals have diverse chemical compositions, nonsilicate minerals display a vast variety of crystalline structures.
Common crystalline structures for nonsilicate minerals include cubes, hexagonal prisms, and irregular masses.
The structure of a nonsilicate crystal determines the mineral’s characteristics.
In the crystal structure called closest packing, each metal atom is surrounded by 8 to 12 other metal atoms that are as close to each other as the charges of the atomic nuclei will allow.
P. 116, 1-9
ls make up 96% of Earth’s crust. Quartz and feldspars alone make up more than 50% of the crust.