1. Growing Crystals

2. EXAMPLES OF HOW TO MAKE CRYSTALS
Liquid to Solid (freezing a melt)
Phenyl salicylate
monoclinic crystals of sulfur
2. From a Chemical Reaction
silver nitrate on copper wire
AgNO Cu › Ag CuNO3
3. From Solution
making copper sulfate crystals OR alum crystals
Borax
each crystal growing activity has its own purpose and why we do it ….You can actually watch the crystals grow and you can see the crystals grow into each other and watch grains and grain boundaries…that is why we do this one…
The light from the stereoscope will be hot enough to keep the phenyl salicylate hot so use a doc camera
Use a bic lighter to melt the phenyl salicylate on a slide and then find the edge of the liquid and drop a seed crystal on it—you can sometimes see crystals appear from no where

3. SOLUTION TERMS Solute: stuff being dissolved
Solvent: stuff doing the dissolving
Water is considered the universal solvent

4. Solution Terms Continued…
Unsaturated Solution
a solution that can dissolve more solute
Saturated Solution
a solution that has dissolved the max amount of solute
the amount of solute a solvent can dissolve increases with temperature
Supersaturated solution
solution that has dissolved more solute than it “theoretically” should

5. What is a solubility curve?
Solubility curve: graph that shows how much of a solute will dissolve in water at different temperatures
Supersaturated
(area above the line)
Saturated
(area ON the line)
Unsaturated
(area below the line)

6. Solubility Graph Examples
How many grams of potassium nitrate can be dissolved in 100g of water at 30 degrees C?
About 24 grams
Find the temperature then follow it up to the line, go to the left to see how many grams you would need
If 70 g of potassium nitrate is dissolved in 100g of water at 40 degrees C...is the solution saturated, supersaturated, or unsaturated?
Supersaturated because its above the line
If 10g of potassium nitrate is dissolved in 100g of water at 50 degrees C, can more potassium nitrate be dissolved? If so, how much more?
Yes, more can be dissolved. About 33 more grams.

7. Ways to form Crystals Cooling a liquid from a melt (freezing)
phenyl salicylate demo
sulfur – monoclinic crystals (Part B)
Grow as a precipitate from a chemical reaction
silver nitrate on copper wire
AgNO Cu › Ag CuNO3
silver nitrate + copper wire -----› silver crystals + copper nitrate
From a solution as the solvent cools or evaporates
growing single crystals – copper sulfate or potassium alum
sodium acetate demo
sulfur – rhombic crystals (Part A)

8. Forming Copper Sulfate Solutions

10. Growing Single Crystals Lab
copper sulfate or potassium alum

11. Day 1
Measure amount of water it takes to fill jar 3/4 full. Use a graduated cylinder. Record in mL.
Determine amount of chemical needed to make a supersaturated solution.
Copper sulfate = _____ mL of water x 0.43 g/mL Or
Potassium alum = _____ mL of water x 0.16 g/mL
Record in grams.
Describe appearance of chemical.

12. Add the amount of water from step #1 to the beaker.
Mass proper amount of chemical into a mL beaker using a balance.
Define the term “tare” in your journal.
Add the amount of water from step #1 to the beaker.
Use a hot plate to heat the contents of the beaker until all of the chemical is dissolved. Stir as you heat.
Pour a small amount of the solution into a watch glass. Place remaining solution into your jar and loosely cap.
Record observations.

14. Day 2 Select a seed crystal from your watch glass.
Cut cm of thread and use it to tie a knot around the seed crystal.
Make a sketch actual size, record the mass and describe the seed crystal in your journal.
Run the thread through the hole in the jar lid and tape it down so that the seed will suspend in the middle of the solution.

15. Clean the seed crystal and thread by gently and quickly dipping them in a beaker of water a couple of times.
Suspend the seed crystal in the jar of solution.

16. Day 2- Journaling
Look at your watch glass under a stereoscope and find examples of each of the following:
single crystal
grains
grain boundary
dendrites are difficult to find – but look in case
Make a labeled sketch of each of these structures.
Choose a seed crystal – sketch it actual size, record the mass and describe it.

17. Day 3+
Check the crystal daily. Record observations, mass, sketches, and describe “maintenance” techniques used.
If crystals appear on bottom of jar – reheat the solution to re-dissolve the chemical. Use a beaker. Allow solution to cool before replacing the crystal.
If dendrites grow on the crystal or thread try to remove them.
use forceps
dip in water
?????????

18. If crystal stops growing, re- supersaturate the solution.
Add 2 or 3 grams of chemical for each 100 mL of solution and reheat in a beaker to dissolve.
Let solution cool before replacing the crystal in solution.

19. Uses of Single Crystals
Turbine blades
PET scanners – scintillating crystals
Lasers
Silicon – computer chips
Uses of Single Crystals

22. Sodium Acetate Demo
growing crystals from a supersaturated solution – sodium acetate and water
journal a description
+acetate&hl=en&sitesearch=# - tower
instant hand warmer

23. Naica Crystal Caves

24. The largest natural crystals on Earth have been discovered in two caves within a silver and zinc mine near Naica, in Chihuahua, Mexico, according to mine officials. Reaching lengths of 50 feet, the clear, faceted crystals are composed of selenite, a crystalline form of the mineral gypsum.

25. Largest Selenite Crystals In The World
The Naica Mine of Chihuahua, Mexico, is a working mine that is known for its extraordinary crystals. Naica is a lead, zinc and silver mine in which large voids have been found, containing crystals of selenite (gypsum) as large as 4 feet in diameter and 50 feet long. The chamber holding these crystals is known as the Crystal Cave of Giants, and is approximately 1000 feet down in the limestone host rock of the mine. The crystals were formed by hydrothermal fluids emanating from the magma chambers below. The cavern was discovered while the miners were drilling through the Naica fault, which they were worried would flood the mine. The Cave of Swords is another chamber in the Naica Mine, containing similar large crystals.

26. In April 2000, brothers Eloy and Javier Delgado found what experts believe are the world’s largest crystals while blasting a new tunnel 1,000 feet down in the silver and lead Naica Mine of southern Chihuahua. Forty-year-old Eloy climbed through a small opening into a 30- by 60-foot cavern choked with immense crystals. "It was beautiful, like light reflecting off a broken mirror," he says.

27. He said that the sight was beautiful “…like light reflecting off a broken mirror”. The translucent crystals lie pitched atop one another, as though moonbeams suddenly took on weight and substance. One month later, another team of Naica miners found an even larger cavern adjacent to the first one.

28. As a professional photographer who specializes in environmentally difficult, narrow and wet canyons worldwide, it was almost impossible to obtain clear photographs even using every trick and technique I know, because of the extreme ambient environment. These crystals are probably stable, as the temperature in the cave is over 150 degrees Fahrenheit with 100% humidity. In other words, these structures are enveloped in steam.

29. As a photographer used to working in dark and dangerous environments, this experience was unique. A human can only function in this environment for six to ten minutes before severe loss of mental functions occurs. I was so excited while photographing the crystals that I really had to focus and concentrate intensely on getting back out the door, which was perhaps only thirty to forty feet away.

30. "Walking into either of these caves is like stepping into a gigantic geode," said Richard D. Fisher, an American consultant with the mining company to develop the discoveries as tourist attractions.
Fisher said that most people can endure only a few minutes in the caves due to their high temperatures.

31. The smaller of the two caves, which is about the size of two-bedroom apartment, is 100 Fahrenheit. The large chamber, which Fisher describes as the size of a Cathedral, is 150 F. Both are located approximately 1200 feet below the surface.

32. The largest previously known crystals were found in the nearby Cave of the Swords, part of the same mine system. Some of these are now on display at the Smithsonian Institution. The local government and mine owners hope to avoid removing any of the new discoveries for museum displays or private collections, Fisher said.

33. While the mine company is currently limiting visitation of the caves to scientific experts, mineral hunters have destroyed locks and broken into the chambers twice since they were first opened by mining equipment last April. One man was killed when he attempted to chop out a gigantic crystal that fell from the ceiling and pinned him.”The heat did him in” according to Fisher.

34. "We need more onsite protection of mine caves," said geologist Carol A
"We need more onsite protection of mine caves," said geologist Carol A. Hill, co-author of the book Cave Minerals of the World, who calls the new discoveries "by far the largest selenite crystals I have ever heard of."

35. Hill applauds the tourism plan
Hill applauds the tourism plan. "Without it, the mining company would probably destroy the caves. Museums have enough crystals," she said. "It's important to preserve discoveries like this where they occur."

36. The mining company plans to air-condition the caves before opening them to the public next year, Fisher said. He adds that reducing the heat gradually will not harm the crystals.

37. Officials of the Penoles Company, which owns the mine, kept the discoveries secret out of concern about vandalism. Not many people, however, would venture inside casually: the temperature hovers at 150 degrees, with 100 percent humidity. A person can stay inside the cave for only six to ten minutes before becoming disoriented.

38. These mountains are 200 million year old limestone massifs hosting networks of caves crossed by very deep hot and mineralized thermal waters. When these waters reached the relatively colder and closer to the surface environments they deposited much of their salt content as lead,zinc and silver .

39. Groundwater in these caves, rich with sulfur from the adjacent metal deposits, began dissolving the limestone walls, releasing large quantities of calcium. This calcium, in turn, combined with the sulfur to form crystals on a scale never before seen by humans.

40.  In addition to 4-foot diameter crystal columns 50 feet in length, the cavern contains row upon row of shark-tooth-shaped formations up to 3 feet high, which are set at odd angles throughout. This crystal form of the mineral gypsum, is known as selenite, named after Selene, the Greek goddess of the moon.

52. When Naica's ores are no longer viable, the mine is closed and the pumping is stopped, then the caves will be submerged - and the crystals will start growing again. The only reason humans can get in the caves at all is because of the ongoing pumping operations that keep them clear of water.

57. Flash with backlighting
Picture with flash only

58. The city of Chihuahua is the state capital of the Mexican state of Chihuahua. It has a population of about 748,551. The predominant activity is light industry.The Naica Mine is located 100km to the N.E.

59. Chihuahua, Mexico is home to two hot caverns containing the largest natural crystals known to man. "Walking into either of these caves is like stepping into a (sweltering) gigantic geode," described one
awed observer. One of the clear selenite crystals is over 50 feet long and weighs over 55 tons.

60. Naica Crystal Cave Of Giants
A forest of crystals, the largest on the Planet. An unreal world, beyond imagination, beyond a dream. A cave with a temperature of 50° C and 100% humidity; an infernal place, where man can survive just a few minutes. Still mostly unexplored.
END
Click to exit

61. Iron Wire Demo

62. Iron Wire – Crystal Structure Change
Iron Wire 72-S to 76-S
BCC slow heating causes the wire to sag due to thermal expansion. The crystal structure of the wire changes to FCC at transition temperature 910o C and the density of the wire increases. As the wire cools back, at the transition temperature, the crystal becomes BCC and the wire will suddenly sag or dip bounce, then return slowly continue to contract to its original length.
Repeat the experiment with a small area of the wire cleaned to remove oxidation. This part of the wire will glow brighter.
The metal magnets will fall off at ~770o , the Curie Temperature
The glowing wire is an example of incandescence – raising the temperature until light is emitted
BCC is loosely packed, at 910C (transition) the wire structure becomes FCC closely packed
Iron atoms are arranged in a body-centered cubic pattern (BCC) up to 1180 K. Above this temperature it makes a phase transition to a face-centered cubic lattice (FCC). The transition from BCC to FCC results in an 8 to 9% increase in density, causing the iron sample to shrink in size as it is heated above the transition temperature.
How it works: A three meter length of iron wire is horizontally stretched above the lecture bench. A Variac supplies the adjustable AC heating current. As the current is increased, the wire will heat up, expand, and sag. The hotter, the more the sag. If the wire is heated to below the transition temperature and allowed to cool (heating current turned off), the wire shrinks back to its original length as is evident by a reduction of the sag to its original. However, if the wire is heated to a temperature above 1180 K (910 C) and then allowed to cool, it behaves in a remarkable way. Initially there is a reduction in the sag as it begins to cool (no surprise). But when it reaches the transition temperature and goes from FCC to BCC, its density decreases, resulting in an increase in overall length (about 2%) and a visible increase in the sag. As it continues to cool back to room temperature the wire shrinks back to approximately its original length. Note that the increase in sag (at the transition temperature) happens very quickly and it is helpful to repeat the demonstration for the class.

63. IRON WIRE OBSERVATIONS AND TERMS
Thermal Expansion
expansion of material due to heat
Incandescence
the emission of light as a result of a material being heated
Curie temperature
the temperature at which magnetic metals lose their magnetism
Curie temperature for iron is 770 °C
Note: 3 naturally magnetic metals: Fe, Ni, Co
In inudstry when moving stell ignets they used to use electromagnets to move it from one part of the plant to the other…you got to wait it to cool below the cuire point before the electromagnet can work

64. OBSERVATIONS Oxidation rusting REMEMBER: METALS ARE CERAMIC WANNABES!
Other observations
heat sink

65. OBSERVATIONS Solid state phase
when a solid material changes crystal structure while remaining a solid
Iron starts off as BCC then changes to FCC it is heated
When it cools it changes back from FCC (more dense) to BCC (less dense) and that is where you see the hesitant pause then rise again
This occurred at 912 °C
Coffee roasters (true hard core ones) use variac to control the the rate at which the coffee bean was extracted
This demo illustrates thermal explansion and packing factor

66. Analysis Questions

67. Face Centered-Densely Packed
Iron Wire – Crystal Structure Change
Face Centered-Densely Packed
Body Centered
More Loosely Packed
912o
Heating
Cooling

68. Iron Wire Crystal Structure
The Curie point of a ferromagnetic material is the temperature above which it loses its characteristic ferromagnetic ability (768°C for iron). At temperatures below the Curie point the magnetic moments are partially aligned within magnetic domains in ferromagnetic materials. As the temperature is increased towards the Curie point, the alignment (magnetization) within each domain decreases. Above the Curie point, the material is purely paramagnetic and there are no magnetized domains of aligned moments.
64-S, 54-M