1. Mineral Crystals and Major Mineral Groups
Section 5.2

2. MI-2 Performance Tasks Define and describe crystal structure.
2. Describe the factors that determine how
minerals grow.
3. Distinguish between minerals by the six basic
mineral shapes.

3. How did these mineral crystals grow to be so large?

5. Mexico's Cueva de los Cristales (Cave of Crystals) contains some of the world's largest known natural crystals—translucent beams of gypsum as long as 36 feet (11 meters). Volcanic activity that began about 26 million years ago created Naica mountain and filled it with high-temperature anhydrite gypsum. When magma underneath the mountain cooled and the temperature dropped, the anhydrite began to dissolve and for millions of years have been deposited in the caves in the form of huge selenite gypsum crystals.

6. Factors that determine crystal size:
Time
Space
Temperature
Pressure
Concentration
Largest uncut diamond found in the Letseng Mine in southern Africa. A near-flawless white gem weighing nearly 500 carats. It was discovered on Sept. 8, 2008 It weighs 478 carats, with very few inclusions and of outstanding color and clarity.

7. 1. TIME and mineral formation
The RATE at which the molten magma cools determines the crystal size.

8. be LARGE and well-formed
If the magma cools at a s-l-o-w rate then the crystals will….
* (example: granite)
be LARGE and well-formed
#44

9. If the magma cools at a fast rate, quickly, then the crystals will….
*example:
obsidian cools instantly so it has no
crystal structure, but a
glass-like structure
be small / microscopic / not well-formed / none

10. Summarize in a sentence:
So…. To grow the biggest, best synthetic diamond crystal, you would….
time,
space,
cooling rate (temperature)
pressure
concentration

11. It takes Gemesis Diamond Co
It takes Gemesis Diamond Co. four days to grow a diamond of an average 2.5 carats. The process begins by placing a microscopic diamond grain into a 4,000-pound machine about the size of a kitchen oven. Under hundreds of thousands of pounds of pressure and at temperatures as high as 2,700 °F, the nugget grows, one atom at a time. It uses about 20 kilowatt-hours per carat,
The Gemesis process mimics a diamond's development deep underground. Apollo Diamond, based near Boston, takes a different tack, imitating the way diamonds are made in space. Through chemical vapor deposition, Apollo's process pumps gas into a chamber that essentially rains carbon and forms a diamond nugget from a "seed" within two to four weeks time.
February 14, :19 PM PST
Synthetic diamonds still a rough cut
By Elsa Wenzel Staff Writer, CNET News

12. Classzone Internet Investigation ES0506 “How Do Crystals Grow?”
2. Space
3. Temperature
4. Pressure
5. Concentration

13. Part A: Make and define a crystal
The regular repeating dendrite (branching) pattern of crystals

14. Part B Concentration and Crystal Formation
Dead Sea: salinity level 33.7% (8.6 times saltier than any ocean)

15. Part C
Space and Crystal Size
Classzone.com activity ES0506…

16. Part D
The effect of the rate of crystal cooling on crystal size and formation
Phenyl salicylate (salol):
What happens to the crystal size formation when it cools slowly?
When it cools quickly?

17. Cooling Rate and the Crystal Size of Granite
Part E
Cooling Rate and the Crystal Size of Granite
Granite contains three main minerals.
quartz
________: clear, whitish, transparent
_______________: pink, salmon-colored
___________________: black, gray, dull
________________: black, shiny
Feldspar (potassium)
Hornblende (amphibole)
Mica - biotite

18. Each mineral melts / crystallizes at its own temperature between 1200ºC and 500ºC
Hornblende

19. Rank the order in which the minerals in granite will crystallize.
First to cool and crystallize ___________
2nd to crystallize ___________________
3rd to crystallize ___________________
Last to crystallize _________________
Hornblende (amphibole)
Biotite mica
Feldspar (potassium) - pink
quartz
So. . . Quartz is the LAST to crystallize, so it is usually shapeless.

21. Part F1
Borax crystals
Salt crystals
Potassium nitrate crystals

22. Crystal Shapes (page 99) Crystal:
the orderly arrangement of the ions, atoms and molecules determines the shape of each mineral’s crystals.

23. Part F2: Crystal Shape Activity
In your note book:
Paper model
letter
Crystal
name
Example Mineral
Tray
sample 1 2 3 4 5 6
Cubic
Tetragonal
Hexagonal
Orthorhombic
Monoclinic
triclinic
F3: Look at the crystal samples in the trays under the stereoscopes.
Match them to the crystal models. A C F D B E
Halite
(Salt)
Zircon
Emerald
Topaz
Sulfur
Gypsum
Mica
turquoise
Use table on page 99 in your text book

24. Minerals as Gems

25. Mineral Gemstones A gemstone is defined as…
What’s the difference between precious and semi-precious stones? What does it mean?

26. Tumbled “Gems” Stones
Gems are valued for their reflective properties due to the way they cut (facets).

27. Rough, uncut vs. polished unpolished
Opal
topaz
emerald
Turquoise
Malachite

28. Our State Mineral Top 5 facts
What is the name of our state mineral?
What color is our state mineral?
3. What elements, the chemical formula
4. Mineral characteristics…
What group of minerals does it belong to
5. How it’s formed…
6. It is found where in Illinois….
7 Value and uses as a mineral resource

29. State Mineral Quiz What is the name of our state mineral?
What two elements make up our state mineral?
It was formed by which method:
magma process,
heat/pressure,
evaporation/precipitation
4. Where in the state is/was it mined?
5. What is an unusual characteristic of it?

30. 5-4-3-2-1 Home work! List the 5 characteristics of a mineral
Describe 4 factors and how they effect crystal size
Describe 3 ways that mineral form
Diagram 2 polymorph forms of carbon
Name the 1 most abundant mineral group in the earth’s crust