Unit 4 – Lesson 1 (Minerals)

Common Traits among Minerals Mineral: a naturally occurring, usually inorganic solid that has a definite crystalline structure and chemical composition.

Definite Chemical Composition Chemical composition is determined when atoms (smallest, indivisible particle of matter) of elements (pure substances) are combined chemically to make compounds. Definite chemical composition means that the arrangement of atoms in the compound do not change.

Solid Matter (anything that has volume and mass) that is in the solid state has a definite volume and shape.

Usually Inorganic Organic means that it is or once was alive. Inorganic means that it does not come from living things and is instead formed in the non-living environment.

Crystalline Structure Crystal: a solid, geometric form that results from a repeating pattern of atoms or molecules. Crystalline structure means that the particular atoms of a specific mineral solidify in a particular pattern.

Naturally Occurring Minerals occur naturally in that natural processes form them; such as evaporating water or high pressure deep underneath the Earth’s surface.

How are Minerals Formed? Minerals form through natural processes. The type of mineral that forms is determined by the type of chemical, the temperature of the area it is forming, and the pressure of the area it is forming.

As Magma and Lava Cools When a volcano erupts, it releases magma. Once cooled, that lava forms many different kinds of minerals.

Metamorphism At the high pressures and temperatures that exist under the Earth, atomic bonds break between existing minerals are reform to make new minerals with new crystalline structures.

From Solutions Minerals can form as water evaporates. ◦Minerals dissolved in water must precipitate on to solid surfaces. ◦Hotter water forms minerals as well. Higher temperature water can dissolve more substances.

Mineral Classification Minerals are classified by composition: ◦Silicate Minerals ◦Nonsilicate Minerals

Silicate Minerals Silicate Minerals are made up of a combination of silicon and oxygen Both Silicon and Oxygen are very common in the Earth’s crust, so naturally 90% of Earths minerals are silicate minerals.

Nonsilicate Minerals Nonsilicate Minerals do not contain the silicon and oxygen tetrahedron. These Minerals can be made up of elements such as carbon, oxygen, fluorine, iron, and sulfur and only make up about 10% of the minerals on Earth.

Classes of Nonsilicate Minerals Native Elements: Minerals composed of one element. Halides: Form when two highly reactive elements form a compound. Sulfates: Minerals that contain both Sulfur and Oxygen. Carbonates: Minerals containing both Carbon and Oxygen. Oxides: When elements form bonds with Oxygen. ex – rust Sulfides: Elements other than Oxygen form bonds with Sulfur.

Identifying Minerals Just like you could discern what ingredients were used in a certain dish by using your taste buds, you can identify mineral by specific properties.

Identifying Minerals Color: ◦Color can identify minerals, but can also be deceiving. ◦Ex. Impurities in quartz can lead to different colors in the crystal.

Identifying Minerals Streak: ◦The color of the powdered form of a mineral is known as streak. ◦You can find out the color of a streak by rubbing the mineral across a streak plate.

Identifying Minerals Luster: the way a surface reflects light ◦Describes the way that the surface of the mineral catches light. Which colors are absorbed and reflected and in what way are the reflected?

Identifying Minerals Cleavage and Fracture: ◦Cleavage occurs when a mineral breaks along flat, parallel surfaces. ◦Fracture occurs when minerals break unevenly

Identifying Minerals Density: ◦Density is measured by how much matter is packed into a given space. ◦Every Mineral has a specific density. Measuring this density can help distinguish between different minerals.

Identifying Minerals Hardness: Mineral’s resistance to being scratched ◦The Mohs scale helps determine the relative hardness of minerals.

Identifying Minerals Special Properties: ◦In addition to the previous methods for identifying minerals, some minerals have special properties that distinguish it from others ◦Ex. Magnetite is magnetic, Calcite causes a double image.