2.0 Rocks and Minerals!

Rocks and Minerals!

2.0 Rocks and Minerals!

A Review of Chemistry!An atom is the smallest particle of matter that contains the characteristics of an element.

Elements and the Periodic Table2.1 MatterElements are the basic building blocks of minerals.

An element is a substance that cannot be broken down into simpler substances by chemical or physical means. Over 100 elements are known. An element is a chemical made of all the same type of atoms.

Types of elements (most common in the Earths crust)Oxygen (O)Silicon (Si)Aluminum (Al)Iron (Fe)Calcium (Ca)Sodium (Na)Potassium (K)Magnesium (Mg)

ElementsWords that MatterA substance is a material with a specific chemical composition.

A compound is a pure chemical substance consisting of two or more different chemical substances.

A mixture is a collection of molecules or atoms of different types.

Rocks and Minerals!

MineralsA mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and definite chemical composition.

Say what?????????????? Lets Break it Down!Lets look at each part of the definition in detail!A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and definite chemical composition. A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and definite chemical composition.

Naturally occurring means that the mineral was made by natural geologic processes over time. Minerals cannot be made by humans!A Silicon Wafer is not naturally occurring!!!

A cubic zirconia is also not natural!

A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and definite chemical composition.Inorganic means that it does not contain carbon. There are a few exceptions such as calcium carbonate (limestone). Peat (partially decomposed organic material) is not a mineral because it is not inorganic=organic!

A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and definite chemical composition.Solid means that the minerals are solid within normal temperatures on the Earth! Of course, they can be melted or turned into a liquid if heated up high enough!Tar: Not a solid AND has carbon so not a mineral!

A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and definite chemical composition.Orderly crystalline structure means that the atoms are arranged in an orderly and repetitive manner. There are a few exceptions to this. Obsidian (volcanic glass) is sometimes not considered a mineral because glass is not a crystal!

A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and definite chemical composition.Definite chemical composition means that the minerals are composed of elements that occur in a consistent ratio.Halite (NaCl=salt) has a definite chemical composition!

2.2 Minerals Summary1. Naturally occurring2. Solid substance3. Orderly crystalline structure4. Definite chemical composition5. Generally considered inorganic

Breaktime!How Are Minerals Formed???2.2 Mineral FormationMinerals form almost everywhere in the Crust under different conditions.

Some minerals form deep within the Crust and others are formed in shallow deposits.

Some minerals form in ocean water and some are made from other minerals that have been crushed and compressed. 2.2 Mineral FormationThere are four major processes by which minerals are formed:Crystallization from magmaPrecipitationChanges in pressure and temperatureFormation from hydrothermal solutions. 2.2 Mineral FormationCrystallization from MagmaAs magma (molten rock) cools, the elements chemically combine to form minerals.

Usually the iron, calcium and magnesium minerals crystallize first. The sodium, potassium and aluminum minerals will crystallize next. 2.2 Mineral Formation: CrystalizationWhen the magma cools, the crystals form.

2.2 Mineral Formation: CrystalizationPrecipitationThe water found in oceans, lakes, streams, and rivers contain dissolved substances in it. When the water evaporates, some of the dissolved substances in the water can crystalize to form minerals.

2.2 Mineral Formation: PrecipitationLimestone and halite (sodium chloride) are two minerals formed by precipitation.

2.2 Mineral Formation: PrecipitationPressure and TemperatureWhen existing minerals are subjected to extreme (high) pressure and temperatures, new minerals can form.

Marble2.2 Mineral Formation: Pressure/TempHydrothermal SolutionA hydrothermal solution is a very hot (between 100 C and 300 C) mixture of water and dissolved substances.

When the solution cools, chemical reactions can take place to form new minerals. 2.2 Mineral Formation: Hydrothermal

Over 3,800 different types of minerals have been identified and named!

These minerals are classified based on their composition.

The major classes of minerals on earth are:Silicates, carbonates, oxides, sulfates/sulfides, halides, and native elements. Can you guess what element each of these groups contain?2.2 Mineral Groups

SilicatesSilicates are the most abundant mineral on Earth!

They contain what two elements?

Yes! They contain oxygen and silicon (usually with other elements too!)2.2 Mineral Groups: Silicates Silicates are made from cooling magma and can occur on the Earths surface or deep within the crust.

2.2 Mineral Groups: SilicatesExamples of SilicatesClay and SandQuartzMicaFeldspar

2.2 Mineral Groups: SilicatesQuartz Often Exhibits Good Crystal Form.

2.2 Mineral Groups: Silicates

Carbonates!Carbonates are the second most common group of minerals.

Carbonates contain carbon, oxygen (CO32-)and one or more other metallic element. 2.2 Mineral Groups: CarbonatesExamples of CarbonatesCalcium carbonate (limestone and marble)DolomiteCalcite (most common carbonate)

2.2 Mineral Groups: CarbonatesOxidesOxides are minerals which contain oxygen plus one or more other elements (often a metal like iron or copper).

Oxides can be made on the Earths surface or deep within the crust.

Oxides often have the name of the metal and then the word oxide such as iron oxide (Fe2O3), copper oxide (CuO2), or aluminum oxide (Al2O3). 2.2 Mineral Groups: OxidesExamples!Copper Oxide

Iron Oxide

Sulfates and SulfidesSulfates and Sulfides contain the element sulfur

FeS2 (pyrite=fools gold)2.2 Mineral Groups: Sulfates-idesGypsum (sulfate) CaSO4 . 2H2O

2.2 Mineral Groups: Sulfates-ides

HalidesHalides are minerals that contain a halogen (fluorine, chlorine, bromine or iodine) plus one or more other elements.

NaCl2.2 Mineral Groups: Halides

Native elements are minerals of a single element such as gold, platinum, silver, carbon

2.2 Mineral Groups: Native Elements Native Copper

Radioactivity is another special property

Pitchblende (uranium)

Lets Review!!!1. The color of the powder left behind when the mineral is scraped across a surfaceStreak2. The way in which light reflects from a minerals surfaceLuster3. The tendency of a mineral to break along flat surfacesCleavage4. The tendency of a mineral to break into irregular piecesFracture5. The visible light that reflects off the mineralColor6. The ability of a mineral to attract a magnet.Magnetism7. The reaction of acid on the mineralReaction to HCl/Solubility8. The light that shines when ultraviolet is shined on a mineral. Fluorescence9. A minerals resistance to being scratched Hardness

GemsGem MineralsDiamondDiamond forms at great depths within the lithosphere, where pressures are in excess of 200 kilobars and temperatures of 800 C or higher. Due to its hardness and resistance to acids ancient Greeks called it adamas meaning the invincible. The rock in which diamonds occur is kimberlite (metamorphosed pegmatite) found in areas of Siberia, South Africa, India, Zaire, Australia, etc. Most commonly diamonds are found in alluvial deposits, but also mined directly from kimberlite (diamond pipes). Less than 25 % of total worlds production of diamonds is suitable for gems. The value of diamonds depends on the four Cs: color, clarity, cut, and carat weight. The most valuable are colorless and blue-white stones. The worlds largest diamond is Cullinan, found in South Africa in 1905. Cullinan weighs 3106 carats (1 carat = 0.2 grams). First diamonds were synthesized in 1955 in the United States.

EmeraldEmerald is green color variety of silicate mineral beryl. Most commonly it occurs in igneous rocks (pegmatite and granite) but also in metamorphic rocks (mica schists). The most valuable emeralds are found in Colombia. Other areas of significant emerald production are South Africa, Zimbabwe, and Russia. Emerald is often considered more valuable than diamond.

RubyRuby is red color variety of oxide mineral corundum. It occurs in metamorphic rocks (marble, gneiss, mica schist) but also in silica deficient igneous rocks such as siyenites. Name of the gem was derived from Latin ruber, meaning red. The most valuable rubies have deep red color, known as a pigeon-blood, and seldom are larger than three carats. The finest Mogok rubies come from Myanmar (Burma). Other areas include Tailand, Cambodia, Sri Lanka, Kenya, etc.

SapphireFrom Latin sapphirus, meaning blue; blue variety of corundum. Sapphires are much more abundant, thus less valuable than rubies. Some of the largest samples exceed 100 carats. The most highly prized are cornflower-blue stones from Cambodia found in alluvial deposits. Other areas of significant production are Tailand, Sri Lanka, India, and Australia.

Semiprecious gems:

PearlOne of the oldest known gems. Certain species of saltwater oysters and freshwater clams build concentric layers of aragonite around sand that penetrates their epithelum (mantle). Pearls may grow flat (blister pearls), irregular (baroque pearls), but most valuable are spherical or drop like pearls. The color of pearls varies with the mollusk species and water environment. The most valuable are rose Indian pearls. Other colors are cream (Persian Gulf and Japan), white with greenish and bluish shades (Australia), black and reddish-brown (Mexico), golden-brown (Panama) etc. The value of natural pearls significantly decreased after huge quantities of cultivated pearls invaded the world market.

AmberAmber is a hardened resin of coniferous trees, usually yellowish brown, but occasionally deep brown to red, green, or blue. Trapped insects, air bubbles, and dust particles may be found in some specimens. The most abundant amber particles are found along the shores of the Baltic Sea, along the coast of Sicily, and Myanmar (Burma).

CoralMarine organisms that live in large colonies in shallow, warm, and clear seas. Their skeletal parts precipitate as aragonite and calcite in many different colors and shapes. The most sought are branch-like corals in red, reddish-rose colors (Mediterranean off the coast of Algeria) and black horn-like corals (Hawaii).