What is a Mineral?

What is a mineral? Minerals are naturally occurring, solid, inorganic compounds or elements.

Did you know… The earth’s crust is composed of about 3000 different minerals! Some minerals have even helped to shaped civilizations and have boosted the economy of the countries that they are found in.

Is it a mineral? Quartz Salt Sugar Coal Pearl Diamond

Characteristics of a Mineral Naturally occurring and inorganic Definite crystalline structure Solid Specific composition

Crystal formed by solidification of a chemical has a highly regular atomic structure

So, what is the difference between a rock and a mineral? Minerals have a unique chemical composition Rocks may carry organic remains Minerals are classified by their chemical composition, rocks are classified by their process of formation. Rocks can be composed of several minerals

Rock-Forming Minerals Out of the 3000 minerals in the earth’s crust, only about 30 are common, and only 8-10 of those are referred to as rock-forming minerals. The most common of these minerals are Quartz, Feldspar, Mica, Pyroxene, Amphibole, Olivine, Garnet, and Calcite.

How Minerals are Formed Some minerals are formed from magma. – Cooling and crystallization – Why do different samples of the same mineral have different size crystals? Some minerals are formed from solutions. – From supersaturated solutions – From evaporation

Identifying Minerals Hardness Streak Test Cleavage Luster Acid Test Specific Gravity Fluorescence Magnetism

Hardness measure of the strength of the structure of the mineral relative to the strength of its chemical bonds

Hardness Moh’s Hardness Scale Can it scratch glass? Can you scratch it with your fingernail? What about with a penny?

Where is the mineral on Mohs’ Scale? Begin by attempting to scratch each mineral with your fingernail. If it scratches using just your fingernail, its hardness is 1-2.

Where is the mineral on Mohs’ Scale? If it does not scratch with just your fingernail, try a penny. If it scratches using the penny, its hardness is 3.

Where is the mineral on Mohs’ Scale? If it does not scratch with a penny, try gently pulling it across a piece of glass. If it does not scratch the glass, its hardness is 4-5

Where is the mineral on Mohs’ Scale? If it does scratch the glass, its hardness is 6-7.

Streak Test color of a mineral in powder form determined by streaking across ceramic tile May be different from color of actual mineral

Streak Test What color is it when powdered on a streak plate? Gold leaves a yellow streak, Fools Gold leaves a black streak.

Cleavage Does it break into flat planes? How many?

Fracture Crystal breakage that is not flat – conchoidal (shell-shaped) or uneven

Why? Question: Why do some minerals break with flat surfaces and some do not? Answer: Some minerals have a regular arrangement of atoms (called crystal structure). This allows them to break with smooth surfaces.

Luster describes how a mineral reflects light from its surface Glassy (vitreous), metallic, dull, waxy, earthy.

Luster What does it look like when the light hits it?

Other tests Acid Test: Does it fizz when acid is dropped on it? Specific gravity: each mineral has a unique density. Fluorescence: Does it look fluorescent under a UV light? Magnetism: Very few minerals are magnetic.

Other Important Terms to Know Opaque: Not allowing light to travel through Translucent: Allowing some light to travel through Transparent: Clear, allowing light to travel through Solubility: The property of a substance to dissolve into another substance. (solvent, solute, solution)

Your Assignment! Complete the graphic organizer. 1.Define and give other important information regarding each property. 2.Using pictures, illustrate each of the physical characteristics or tests that are used to identify minerals: – Luster – Hardness – Streak – Cleavage – Acid Test – Specific Gravity – Magnetism – Fluorescence