Mineral Properties Key Concepts n A pure substance

+ Mineral Properties

+ Key Concepts n. A pure substance, such as a mineral, can be identified from observations and tests performed to determine its physical properties. These properties are based on the unique structure of the substance. n Minerals are crystals that form naturally in the Earth. They have characteristic properties, such as color, hardness, and a crystalline shape. n Rocks are made of minerals.

+ General Vocabulary Geologist – scientist who studies the Earth and the changes that take place on and beneath the surface Rock – a naturally occurring solid substance composed of one or more minerals.

+ General Vocabulary Mineral – a naturally occurring solid material that has a specific chemical composition and crystal form and characteristic physical properties. n. There about 3, 800 different minerals.

+ General Vocabulary Mineral Characteristics: 1 Forms in nature 2 Is a solid 3 Has a definite chemical make-up 4 Has a crystal structure

+ Mineral Characteristics 1 Forms in nature 2 Is a solid 3 Has a definite chemical makeup 4 Has a crystal structure n Formed by natural processes. n It has been estimated that garnets can grow about one atomic layer per year (a two centimeter crystal growing over a period of ten million years) n Are inorganic which means they are made of non-living materials found naturally on earth.

+ Mineral Characteristics 1 Forms in nature 2 Is a solid 3 Has a definite chemical makeup 4 Has a crystal structure n. A mineral has a definite volume and a rigid shape. n Volume refers to the amount of space an object takes up

+ Mineral Characteristics 1 Forms in nature 2 Is a solid 3 4 Has a definite chemical makeup Has a crystal structure n Every mineral consists of a specific combination of atoms of certain elements. n The types of atoms that make up a mineral are part of what makes the mineral unique. n n The way in which the atoms are bonded, or joined together, is also important. Many properties of minerals are related to how strong or weak the bonds are.

+ Mineral Characteristics 1 Forms in nature 2 Is a solid 3 Has a definite chemical makeup 4 Has a crystal structure n Each mineral has its own type of crystal structure. n Minerals can have the same chemical compound/same type of atoms, but the way the atoms are arranged is different. n Diamonds and graphite are made of the same element, carbon, but the arrangement of these carbon atoms is different.

+ Side Note… …look at the following minerals: Which do you think are the same types of minerals and which do you think are different?

+ TRICK QUESTION!!! These are all the same type of mineral! They are all examples of quartz!!

+ Why Is It So Difficult to Identify Minerals? n There are over 3800 types of minerals in the Earth’s crust n As you could see with the quartz, often times even the same kind of minerals can look very different n Therefore, geologists (scientists who study minerals and rocks) often use several different tests to determine type of a mineral they have found!

+ Mineral Properties Minerals have characteristic properties that are used to identify them: n. Color n. Luster n. Transparency n. Streak n. Cleavage & Fracture n. Crystalline Structure n. Texture n. Hardness

+ Mineral Properties n Color n Luster n Transparency n Streak n Cleavage & Fracture n Crystalline n Texture n Hardness Structure Color is obviously one of the most noticeable characteristics of a mineral, but it also the least reliable of all the characteristics n The color of a mineral is often caused by tiny amounts of other elements or compounds inside n For example, what people call amethyst is actually just quartz with iron in it!

+ Mineral Properties n Color n Luster n Transparency n Streak n Cleavage & Fracture n Crystalline n Texture n Hardness Structure n The way that a mineral reflects light from its surface is its luster n The two types of luster are: - metallic - nonmetallic

+ Mineral Properties n Color n. A n Luster n Transparency n Streak n Cleavage & Fracture n Crystalline n Texture n Hardness Structure mineral’s degree of transparency: ability to allow light to pass through it. n The degree of transparency may also depend on the thickness of the mineral. n Also known as “Diaphaneity”

+ Mineral Properties n Color n Luster � When a mineral is rubbed against a tile, it will leave behind a colored powdered streak on the tile � Sometimes a mineral’s streak does not match the mineral’s external color � For example, one way to tell the difference between pyrite (Fool’s gold) and real gold is by streak. Pyrite leaves a greenish-black streak while real gold leaves a yellow streak. n Transparency n Streak n Cleavage & Fracture n Crystalline n Texture n Hardness Structure

+ Mineral Properties n Color n Luster n The n Transparency n Streak n Cleavage n. A & Fracture n Crystalline n Texture n Hardness pattern of atoms will determine how a mineral will break Structure mineral that breaks relatively easily and evenly at angles is said to have cleavage n Minerals that break with rough or jagged edges are said to have fracture

+ Mineral Properties n Color n Luster n Mineral n Transparency n Streak n Cleavage � The & Fracture n Crystalline n Texture n Hardness crystals occur in various shapes and sizes. Structure regular pattern of atoms, molecules or ions in a crystal. � Atoms in a mineral are arranged in a systematic and repeating pattern

+ Mineral Properties Talc has a soapy texture. n Color n Luster n Transparency n Streak Fluorite has a n Cleavage & Fracture glassy texture. n Crystalline n Texture n Hardness Structure n Texture describes how a mineral feels to the touch. n Minerals can range anywhere between glassy feeling, rough feeling, greasy feeling, and even soapy feeling!

+ Mineral Properties n Color n Luster n Hardness n Transparency n Streak n Cleavage & Fracture n Crystalline n Texture n Hardness Structure is a measure of how easily a mineral can be scratched n Geologists use Mohs Scale to give minerals their hardness ratings