Minerals Objectives•List 5 characteristics all minerals share•Give examples of 2 ways that minerals form•List the physical properties to identify minerals•Describe how physical properties are used to identify minerals•List characteristics that gems have that make them different from and more valuable than minerals•List the conditions necessary for a mineral to be classified an ore•List the properties of titanium that make it useful in biomedicine•Identify the minerals that are mined for titanium

What is a Mineral?

• A mineral is a naturally occurring,

inorganic solid

with crystalline form

and definite chemical composition.

The Structure of Minerals

• Crystals – a solid in which the atoms are arranged in repeating patterns: Go to Pg. 63 and draw each sample by their pattern name. Due Thursday at the beginning of class.

• 1. Cubic• 2. Tetragonal• 3. Hexagonal• 4. Orthorhombic• 5. Monoclinic• 6. Triclinic

Mineral Formation1. Magma formation- cooling of hot molten rock material -Atoms lose energy and move closer together, patterns.2. Liquid evaporation- minerals dissolved in liquids -Liquid evaporates atoms of minerals stay & form crystals3. Precipitation- alternate material in supersaturated

solutions

Mineral Identification

1. Color 2. Luster3. Streak 4. Hardness5. Cleavage 6. Fracture7. Crystal form 8. Density9. Specific gravity 10. Magnetism11. Reaction to hydrochloric acid (HCl)12. Taste13. Fluorescence14. Double refraction

1.Colornot always diagnostic (feldspar, quartz, fluorite)

                                                                                                            

Feldspar can be green, pink white, gray, etc.

2. LusterMetallic, non-metallic      glassy or vitreous, dull, pearly,      resinous, waxy, adamantine, silky

3. StreakUsing a unglazed porcelain plate scratch the porcelain and note color, odor if any.

                                                                          

   

  1.Both of these samples are hematite; both have a reddish-brown streak

4. Hardness Moh’s Scale of Hardness (1-10)

1.Talc 6. Orthoclasefeldspar(Kfeldspar)2.Gypsum ____ fingernail 7. Quartz3.Calcite ___ penny (copper) 8. Topaz. 4.Fluorite ___ iron nail 9. Corundum5.Apatite ___ glass 10. Diamond

Minerals Objectives•List 5 characteristics all minerals share•Give examples of 2 ways that minerals form•List the physical properties to identify minerals•Describe how physical properties are used to identify minerals•List characteristics that gems have that make them different from and more valuable than minerals•List the conditions necessary for a mineral to be classified an ore•List the properties of titanium that make it useful in biomedicine•Identify the minerals that are mined for titanium

5. CleavageBreakage along planes. Related to crystal structure

1 direction(muscovite, biotite)

                                                            

Muscovite (left) Biotite (right)

2 directions at 90°(feldspar, pyroxene)

                                            

  Pyroxene

3 directions at 90° (cubic)(halite, galena)

  

 Halite Galena

3 directions not at 90°(rhombohedral)(calcite, dolomite)

                                                            

Cleavage fragments of calcite Cleavage fragments of dolomite

4 directions (octahedral)(fluorite)

                                             

Cleavage fragments of fluorite Sphalerite

6 directions(sphalerite)

6. Fractureirregular breakage (no cleavage), breakage not along smooth planes

Conchoidal fracturesmooth curved fracture surfacesoccurs in quartz, chert, obsidian, glass

Rose quartz and obsidian lacks cleavage; they have conchoidal fracture

7. Crystal formSome minerals that may or may not have cleavage GROW (not break) into crystals with flat sides. quartzpyrite

Quartz crystals

Physical Properties cont.8. Density : D=mass/volume9. Specific gravity (similar to density) Weight of

a mineral divided by weight of an equal volume of water.

10. Magnetism: Can be picked up by a magnet or may be a natural magnet.

11. Reaction to hydrochloric acid (HCl) Calcite effervesces in acid.12. Taste : halite, sylvite13. Fluorescence: Some minerals glow in the

dark under a black light (U.V. light) Due to excitation of electrons

14.Double refraction Light passing through the mineral is split into two rays. Causes an optical "doubling" effect. Calcite

                                                                                                             

Calcite has the optical property of double refraction. In the photos above, the same sample of calcite is used. It is rotated over a thin dark line. Examine how the appearance of he line changes in the different orientations of calcite.

Mineral Composition and Groups

• 90 elements occur naturally in Earth’s crust.

• 98% of the crust is made of only 8 elements 46.6% Oxygen, 27.7% Silicon, 8.1% Aluminum, 5% Iron,

3.6% Calcium, 2.8% Sodium, 2.6% Potassium, 2.1% Magnesium, 1.5% others

• 4000+ known minerals, a few dozen are common and these are composed of the 8 common elements

Minerals Objectives•List 5 characteristics all minerals share•Give examples of 2 ways that minerals form•List the physical properties to identify minerals•Describe how physical properties are used to identify minerals•List characteristics that gems have that make them different from and more valuable than minerals•List the conditions necessary for a mineral to be classified an ore•List the properties of titanium that make it useful in biomedicine•Identify the minerals that are mined for titanium

Major Mineral Groups

• Silicates – SiO2 – silicon, oxygen + element

• Carbonates – CO3

• Oxides – element + Oxygen (O2)

• Sulfides – element + sulfur (S)

• Sulfates- SO4

• Halides – Salts with( +) or( –) ions • Hydroxides- OH

• Phosphates – PO4

• Native elements – single elements ( Au, Ag, Cu)

Uses of Minerals

• Gems: have crystal structure which allows them to be cut and polished

• Rare and beautiful• Brighter and more colorful

Ex: Opal

More Gemstones

Azurite andMalachite

Ores: are minerals which contain a useful substance which can be mined for a profit.

• Bauxite – Aluminum• Hematite – Iron • Sphalerite – Zinc• Chalcopyrite - Copper

Ores continued:Waste Rock Removal- Cost –vs- demand:In order to get the ore waste material must be removed first. This may be costly both on the $ end and to the environment. If the cost of the removing of the waste gets higher than the value of the desired material, then it is no longer considered an ore.

Zinc:Sphalerite

Copper:For coins, wireChalcopyrite

Technology and Minerals

Rutile: produces Titanium which is lightweight, durable, and nontoxic. Used in bicycles, airplanes, hip replacements. Most titanium is mined from rutile rather than ilmenite because the mining and processing from ilmenite is hazardous to the environment.

Minerals as Paint Pigments

Many minerals used as pigments were poisonousLead, arsenic, mercury. Cinnabar – red (mercury)Greens and blues: malachite and azurite.Dark blue ultramarine: lapis lazuliOchre: yellow clay containing iron.White: from compounds containing; calcium, zinc, titanium and lead.