1. Crystal Cave in Mexico, discovered a few years go
Crystal Cave in Mexico, discovered a few years go. Gypsum crystals Factors: space, time, concentration (amount) temperature, pressure

2. The 5 characteristics of a mineral
Solid
Natural (found in nature)
Inorganic (never living)
Orderly internal structure of atoms (crystal structure)
Chemical composition (chemical formula)
We’re going to look at the internal arrangement of the atoms, molecules that give a mineral its crystal structure

3. Essential Question:
How do minerals crystals form and what factors affect the size and shape of crystals?

4. Unit 4 Crystal Formation
PHENOMENON:
What did you observe?
What evidence do you have?
OBJECTS: .
What objects are interacting?
MOTION /STRUCTURE
Describe the structure that in the model that explains your observations
 copper wire and silver nitrate
Salt solutions in 100% and 10% concentrations
Salol cooling and crystalizing
Granite rock crystals
Graphite and diamonds

5. Part A: Making (silver) Crystals
How does a mineral crystal form ‘grow’? Show snowflake clip and rock candy sample. Do copper and silver nitrate lab
Snowflake Formation
Crystal formation of Potassium Chromate

6. Silver nitrate ‘crystals’ pic from phone
Although not completely flat surfaces,
the silver
atoms arrange
in a regular repeating
pattern
Definition of
crystal

7. How Minerals Form page 97
Magma Pressure Process Evaporation Process (Precipitation) Process
(most)

8. Part B: Concentration and Crystal Formation
Evaporation/Precipitation process of mineral formation
1. Ions (such as salt or calcium) are dissolved in water.
2. The water EVAPORATES, and the ions form minerals
such as halite, calcite, gypsum, limestone.

9. Different Concentrations: different amounts of salt dissolved in solution

10. Part C: Crystal and Space
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 m). Volcanic activity 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 gypsum that had been dissolved for millions of years began to be deposited in the caves in the form of huge selenite gypsum crystals.

11. 100% concentration
25% concentration
100% concentration 25% concentration

12. Draw Particle diagrams to show (model) how the crystals formed out of a solution
We can’t ‘see’ the atoms/ions/molecules arrange themselves, draw PARTICLE diagrams to show/model what’s going on at the molecular level.
Salt dissolved in water % salt solution water evaporated and salt arranged into
100% concentration crystals
Water salt

13. White Board Session review
WB is neat, organized, readable
All members of the group are prepared to explain a part of the WB
All group members are prepared to answer questions about the WB
Address questions and answers to the entire class
No judgment statements –ask good questions
It’s okay to make mistakes –that’s how we learn
Be respectful of the presenters.
Every student is responsible for all the information learned from the discussion

14. Factors that determine crystal size:
Concentration
Space
Time / rate
Show ES0506 and discuss as a class. Time, space, temperature, pressure, concentration
ES0506
Outside inside

16. Part E: Observe crystals
Under a stereoscope, compare the size of the crystals for 3 magma rocks Granite Basalt Obsidian

17. The Magma Process: (pg.97)
Molten (liquid) rock in a magma chamber
At, near or under earth’s surface, rises
The magma begins to COOL.
The atoms, ions and molecules combine
to form various mineral compounds.
The molecules arrange into an orderly repeating pattern to form CRYSTALS.
quartz

18. Rate / Time
The RATE at which the molten magma cools determines the crystal size.
Predict:
If the magma cools s-l-o-w-l-y
(under the surface taking hundreds of years)
then the crystals will be…
granite
well-formed

19. If the magma cools quickly (weeks) the crystals will be small / microscopic / not well-formed
(Look at basalt with a hand lens or scope)
Predict:
If the magma cools at a very fast rate, quickly, then the crystals will…. None
example:
obsidian a volcanic rock, cools instantly.
so it has no crystal structure, but a
glass-like structure

20. Crystallization of Salol Lab
Slow cooling and crystalizing
FAST cooling and crystalizing
Slow cooling allowed for larger, well-defined crystals

21. Size of crystals in Granite
Part E: Rate of Cooling and
Size of crystals in Granite
Granite contains 3-4 main minerals.
quartz
________: clear, whitish, transparent
_______________: pink, salmon-colored
___________________: black, gray, dull
________________: black, shiny
Feldspar (potassium)
Hornblende (amphibole)
Mica - biotite

22. Rank the order in which the minerals in granite will crystallize.
Each mineral melts / crystallizes at its own temperature between 1300ºC and 500ºC
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 ______________________
Olivene
Biotite mica
500°C
Potassium Feldspar
But this variation in cooling temperatures and times explains the appearance of so many different crystals in Granite.
Different minerals in granite crystalize at different temperatures. The last to cool has limited space to form crystals – so smaller not well-formed crystals
Quartz
So. . . Quartz is the LAST to crystallize, so it is usually shapeless. It essentially cools and forms around the other minerals that have already cooled and formed.

23. The kind of mineral that is formed depends on…
1. Which elements are present when it forms
2. The amount of an each element present.
* The same magma chamber can form different minerals.

24. Bellwork What is the #1 most abundant element in the Earth’s crust.
2. List the five characteristics of a mineral:
3. What is the hardest and softest mineral on the Moh’s Scale of Hardness?
4. Define a crystal:
5. How does a fast rate of cooling affect the size of
crystals? Slow rate?

25. Factors that affect the size and shape of crystals
Concentration
Space
Time / rate
Temperature
Pressure
Where do diamonds form?

26. The Pressure Process:
1. Rock or mineral is exposed to extremely high pressures and temperatures, and the minerals begin to break down.
2. As pressure and temperature increase, the molecules RE-FORM into new minerals!

27. Upper mantle

28. Compare the properties of a diamond and graphite
Color Luster Hardness Cleavage Crystal structure

29. Graphite and diamonds are BOTH made of just CARBON atoms Make a particle diagram of the atoms
graphite diamond
Remind them of the particle diagram they did of MICA; loose bonds between layers.

30. Synthetic, man-made diamonds
It takes Gemesis Diamond Co. four days to grow a diamond of an average size of 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.
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.
Genisis diamonds
Synthetic Diamonds

31. Both diamond and graphite contain only carbon atoms.
Polymorphs. Minerals which have the same chemical make-up, but different crystal structures
Both diamond and graphite contain only carbon atoms.
Diamond is the hardest mineral b/c its atoms are tightly bonded. Graphite is one of the softest b/c it has weak bonds between its layered structure.

32. Part F: Crystal Shapes (page 99)
the orderly arrangement of the ions, atoms and molecules that determines the shape of each mineral’s crystals.
Do Mineral Formation Lab

33. Salt crystals Potassium nitrate crystals

34. Part F: Crystal Shape Activity
Paper model
letter
Crystal
name
Example Mineral
Tray
sample 1 2 3 4 5 6
Cubic
Tetragonal
Hexagonal
Orthorhombic
Monoclinic
triclinic
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

35. Graphing Factors that affect crystal growth:
Concentration
Space
Time to cool or Rate of cooling
Temperature
Pressure
Select TWO factors and construct two graphs that show the relationship between them and crystal size and shape.

36. Example: If…. Crystals had enough SPACE to form A lot of large,
well-formed
crystals
Few, shapeless crystals
Low concentration of material high