1. Minerals

2. What is a Mineral? Solid Naturally Occurring Inorganic
Definite Crystal Structure
Definite Chemical Formula

3. Minerals are Identified by their Physical and Chemical Properties
Crystal Structure
Color
Luster
Streak
Breakage
Reactions with Acid
Other Special Properties
Hardness
Specific Gravity (Density)

4. Crystal Shape Cubic Monoclinic
the crystal shape results from the atomic arrangement into geometric patterns when the mineral forms
Cubic
Monoclinic

5. Color
Usually the first and most easily observed but the least accurate property
-one mineral may come in many colors; the color is the result of minor impurities
-bottle makers took advantage of this fact
glass with gold
Silicon from Michigan had iron in it so the bottles were green. When that source was depleted, Coke used other material and the bottles were white.

6. Changing Color in Glass and Minerals
Compounds Colors
iron oxides greens, browns
manganese oxides deep amber, amethyst, decolorizer
cobalt oxide deep blue
gold chloride ruby red
selenium compounds reds
carbon oxides amber/brown
manganese, cobalt, iron black
antimony oxides white
uranium oxides yellow green (glows!)
sulfur compounds amber/brown
copper compounds light blue, red
tin compounds white
lead with antimony yellow

7. Color
-different minerals are the same color

8. Luster appearance of a mineral’s surface as it reflects light
Metallic – look like shiny car
Nonmetallic
Glassy shine
Muted shine
Dull shine

9. Streak
Color of the mineral’s powder as determined by rubbing the mineral on a piece of unglazed porcelain called a streak plate

10. Breakage
Minerals break along lines of weakness in their crystal structure
Cleavage occurs when a mineral splits or cracks along flat planes
Fracture occurs when a mineral breaks at random lines

11. Reactions with Acid
Minerals in the Carbonate Family (-CO3) react chemically with acid to produce carbon dioxide gas
Reaction creates bubbles of gas and the mineral appears to fizz

12. Hardness Mohs Scale Mineral hardness was in use as long ago as 300 BC
Current system was invented by German scientist in 1812
Based on a mineral’s resistance to being scratched

13. Minerals in Mohs Scale
softest
hardest

14. Hardness In the field, common objects are used to determine hardness.
>2 fingernail
3 penny
~5 steel of a pocket knife
5.5 glass
6.6 steel of a file
7 quartz crystal
emery

15. Modern Versions of the Brinell Hardness Tester
A hardness test for metals was developed by Swiss engineer Johan August Brinell in He evaluated strength by using a tiny cannon to shoot small steel balls into a sample and mathematically analyzing the results.
Modern Versions of the Brinell Hardness Tester

16. Sapphire is related to Corundum, #9 on Mohs Scale
Apple was trying to develop sapphire screens for iPhones.

17. Special Properties Magnetism Taste Smell Fluorescence Phosphorescence
Refraction
Electrical
Radioactive

18. Specific Gravity
Similar to density, which is the amount of matter in a given space (Mass/Volume)
Compares density of the sample with the density of water
Determined by dividing the mass of the sample by an equal volume of water
<3 is nonmetal, >5 is metallic
Tells you how many times more dense than water the mineral is