Chapter 5 Lithosphere Rocks & Minerals

Minerals Fist List High Five!! What is a Mineral?

Solid, Earth Material What does that mean?!?!?! --Not a gas or a liquid --Has a definite shape and volume Solid, Earth Material QUESTION? Is oil a mineral?? Answer… No, because it is a liquid.

What does that mean?!?!?! Naturally Occurring --Not man-made

Inorganic What does that mean?!?!?! --Not formed from living things or the remains of living things --NON-LIVING!! EXAMPLES Coal is NOT a mineral because it comes from plants. Amber is NOT a mineral because it comes from tree sap. A pearl is NOT a mineral because it comes from oysters.

Definite Chemical Formula What does that mean?!?!?! --The elements that make up the minerals are combined in definite proportions Definite Chemical Formula EXAMPLES -Gold (Au) -Pyrite (FeS²) -Graphite (C) -Diamond (C)

Definite Crystal Structure What does that mean?!?!?! --Atoms are arranged in a repeating pattern --Each mineral has a different INTERNAL ARRANGEMENT OF ATOMS that gives it distinct physical and chemical properties Definite Crystal Structure

What does that mean?!?!?! Definite Crystal Structure QUESTION ANSWER How does the mineral graphite, which is soft have the same chemical formula as diamond, which is the hardest mineral in the world? Definite Crystal Structure ANSWER Because their internal arrangement of atoms are different

Minerals in Your House http://www.mineralogy4kids.org/minerals-your-house

How are Minerals Identified?? Fill in the spiders legs as we go!!

Minerals can be identified by their chemical and physical properties.

Classifications of Minerals Silicate Contains silicon, and oxygen Make up 96%of Earth’s crust Non Silicate Make up 4% of Earth’s crust Does not contain silicon or oxygen Major classifications Carbonates, halides, native elements, oxides, sulfates, & sulfides (know this list for the quiz)

Minerals are identified by their key characteristics hardness crystal shape (form) luster color streak cleavage/fracture density (specific gravity) special properties --reaction to acid --fluorescence --salty taste --magnetism

Color How are Minerals Identified?? --Least useful for identification --One mineral can come in many colors EXAMPLE: --Hematite: Comes in black, red and brown

Color results from ability to absorb some wavelengths and reflect others some minerals have characteristics colors others vary due to chemical differences or impurities (atoms mixed inside the main elements) http://www.minerals.net/mineral/carbonat/calcite/images/4assortd.htm

How are Minerals Identified?? 1. Some minerals are always the same color Sulfur 2. Some minerals can have many colors Rose Quartz Quartz Smoky Quartz

Colors can vary as a result of… Chemical Impurities– Cobalt compounds tend to be pink, purple, or blue Manganese—tends to produce pink colors

Colors can vary as a result of… B. Oxidation—exposure to air and water changing the color of the mineral. Ex. Rust --Iron is the dominant coloring agent in rocks and soils

Streak How are Minerals Identified?? --the color of a mineral when it is finely powdered --determined by rubbing the mineral on a piece of tile Streak Hematite has a reddish-brown streak.

Streak Color of the powder when rubbed on a “streak plate” (unglazed porcelain) Some paint is based on powdered minerals (streaks). http://www.minerals.net/mineral/oxides/hematite/hematit6.htm

Luster How are Minerals Identified?? --describes how a mineral appears to reflect light There are 2 categories in which a minerals luster can fall… Luster Metallic OR Non-Metallic

Luster Describes how light reflects off the surface Main categories are “metallic” and “non-metallic” Non-metallic includes “dull,” glassy,” waxy,” “pearly,” and othershttp://www.minerals.net/mineral/sulfides/pyrite/pyrite2.htm http://www.minerals.net/mineral/sulfides/pyrite/pyrite2.htm

How are Minerals Identified?? A. Metallic– reflects light like metal (shiny) Graphite Galena Pyrite

How are Minerals Identified?? B. Non-Metallic—any mineral which DOES NOT exhibit shiny metallic characteristics Ex. Quartz

Metallic or Non-Metallic?? Mica Pearly luster Metallic Magnetite

Metallic or Non-Metallic?? Pyroxene Dull luster

Hardness How are Minerals Identified?? --Resistance of a mineral to being scratched --Moh’s Hardness Scale—compares the hardness of the mineral to 10 reference minerals. Hardness

Mineral Hardness Ability to scratch another mineral Mohs Hardness Scale from 1 (talc) to 10 (diamond) Quartz (most common mineral and most dust particles) is 7 http://mineral.galleries.com/minerals/elements/diamond/diamond.htm

How is Hardness Determined?? The scale consists of number 1 through 10; 1 being the softest and 10 being the hardest. Each number represents a different mineral- each harder than the previous. The 10 minerals are to the left. Softest Hardest

How is Hardness Determined?? Several common household items have a fixed hardness, and can be used to test for hardness. -Fingernail = 2.5 -Copper penny = 3-3.5 -Nail = 4.5 -Knife blade = 5.5 -Glass = 5.5 -Steel file = 6.5 -Streak plate = 7

What Determines Hardness? --Hardness is determined by a minerals internal arrangement of atoms. Ex. Diamond vs. Graphite -Diamond has hardness of 10 and graphite is ranked between 1 and 2. Diamond is about 40 times harder than graphite due to the way the atoms are arranged. --Hardness is the best property to use to identify a mineral.

Cleavage or Fracture How are Minerals Identified?? Cleavage—when a mineral breaks along a flat, smooth surface Cleavage or Fracture

Examples of Minerals that show Cleavage Mica exhibits basal cleavage. Galena exhibits cubic cleavage.

What Determines Cleavage and Hardness? A minerals internal arrangement of atoms!!

How are Minerals Identified?? Fracture—When a mineral breaks along irregular rough surfaces. EX. Quartz Cleavage or Fracture

Mineral cleavage/fracture Some minerals split along flat surfaces when struck hard--this is called mineral cleavage Other minerals break unevenly along rough or curved surfaces--this is called fracture A few minerals have both cleavage and fracture

Density or Heft How are Minerals Identified?? --The amount of matter in a given space (mass/volume) Depends on… -kind of atoms which make up the mineral -how the atoms are arranged in the crystal lattice Density or Heft

Density (Specific Gravity) All minerals have density (mass / volume), but some are very dense Examples include galena, magnetite, and gold Specific Gravity is the density of the mineral compared with density of water (1g/ml) http://www.minerals.net/mineral/elements/gold/gold1.htm

Crystal Shape How are Minerals Identified?? --Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming Crystal Shape

Crystal Shape (Form) External structure due to internal arrangement of the atoms Six basic groups of shapes, with about three dozen variations http://www.minerals.net/mineral/carbonat/aragonit/aragoni1.htm

Special Properties How are Minerals Identified?? -Magnetism (Magnetite) -Fluorescence & Phosphorescence -Salty taste (Halite) -Smell (Sulfur) -Chatoyancy & Asterism Special Properties

Special Characteristics-- Fluorescence & Phosphorescence Some minerals will glow when placed under short-wave or long-wave ultraviolet rays (fluorenscence) Some minerals will continue to glow when the light is turned off (phosphorescence) http://www.sterlinghill.org/Tour%20information.htm

Special Characteristics-- Salty Taste DO NOT TASTE MOST MINERALS! Halite is the exception--it will taste salty http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Halides+Halite

Special Characteristics-- Magnetism Many iron minerals will produce an invisible magnetic force field “Lodestone” was used by Vikings more than 1,000 years ago as compasses http://www.minerals.net/mineral/oxides/magnetit/magneti4.htm

Special Properties Chatoyancy Asterism Light reflects and gives the appearance of a “cat’s-eye” Similar to Chatoyancy however, the effect is a 6 sided star shape