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Observe Salol Crystals

Day 7
by

Summer Roland

on 29 May 2014

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Transcript of Observe Salol Crystals

Day 7 - Observe Salol Crystals
Explain why this is true:
When a metamorphic rock is forming, it may be subjected to extremely high temperatures, yet it never completely melts.





When an igneous rock forms deep underground, is it likely to harden slowly or quickly?

If a metamorphic rock melts completely it becomes molten rock. Therefore if molten rock cools and hardens it is igneous and not metamorphic anymore.
It is likely to harden slowly because it is extremely warm deep underground.
Labels
Naming Labels
Quartz
Pyroxene
Feldspar
Labels are short pieces of text or writing that occur inside a diagram and they are very important to understanding the diagram.
There are two types of labels

- Naming Labels, identify or "name" parts of a diagram.
- Explanatory labels, provide more information about a particular part of a diagram.
Explanatory Labels
Captions
Captions have several uses:
to identify what is important in an image.
say what art of the image to pay attention to.
You should ALWAYS read the caption even if you think you know what the image is illustrating.
Quartz
Pyroxene
Feldspar
Without a caption, it is difficult to know much about this image
Quartz
Pyroxene
Feldspar
With a caption in place, the viewer has the necessary information.
As magma cools, different minerals come together to form crystals, as in this granite. The crystals grow together, filling the spaces.
The caption provided information about how the granite formed (minerals formed crystals as the magma cooled) that could not be understood from just the labeled image itself.
Describe what the image illustrates.
QUESTION:
* Crystals might form at the time igneous rocks form from magma or lava.
* Igneous rocks start as molten magma.
* It takes a lot of heat to melt a rock.
* The lowest temperature at which some rocks will melt is 750°C.
COLLECT INFORMATION:
COLLECT INFORMATION:
*We won't be able to melt any rocks in our classroom, but I do have a material that we can use to simulate the heating and cooling of rock.
*This material is called salol.
*It melts at the temperature of hot water coming from the tap.
*** The bottles are to remain closed for the entire investigation for your safety.***
OBSERVE
Take several minutes to observe what happens inside the bottles when they are heated and cooled.
What did the salol look like before you placed it in the hot water?



How long did it take for the salol to melt?



What happened when you placed the salol in the cold water?



What did the crystals look like?
The salol had white crystals on the sides of the bottle.
The salol took about a minute to melt.
The salol started to get hard. It turned back into crystals.
Some crystals look like crushed ice or big sugar crystals; others look like flat needles and featherlike branches, often growing in rosettes from a central point or circle.
Crystallization
> Crystal shape is one of the properties that geologist use to help them identify minerals.
> Most minerals have a characteristic crystal form.
> Salol crystals form the same shapes each time they crystallize.
> Small crystals look like needles and feathers, large crystals may be diamond-shaped, and large clumps of crystals look like broken ice.
COLLECT INFORMATION
COLLECT INFORMATION
FORMING A HYPOTHESIS:
IF the temperature, location, cooling time, bottle position are changed, THEN mineral crystal formation will be larger or smaller.

What are some of the variables that might affect the size of crystals that form?
Some variables that might affect the size of crystal
formation are temperature
rate of cooling
length of time in the hot water
the way the bottle lies as it cools.
How could you design an investigation to find out what effect these variables have on crystal size?
Do some igneous rocks have larger crystal formations than others?
* Set 1 are all igneous rocks that you have identified.
When you get set 1 this time look for crystals - pieces of pure minerals in the rocks.
* Ask yourself this as you look, "Is there a relationship between crystal size and whether the igneous rock was intrusive or extrusive?"
-> In order to identify a mineral, you need to observe it properties – characteristics that help identify it.
-> There are 5 main properties that we use to identify.
-> There are many minor properties that can also help id a mineral.
Mineral Property #1: Color & Streak
- Many minerals have different colors and some minerals' colors are identical to other minerals' colors.
- Color is the first thing someone notices when they view a mineral.
- Color is also one of the big reasons that attract people to minerals.
- Generally speaking, color is not a good property to be used in the identification of minerals. It is usually the first property to confuse a novice collector into making an incorrect identification.
Mineral Property #1: Color & Streak
-
Streak
is closely related to
color
, but is a different property because the color of the mineral may be different than the color of the streak.
-
Streak
is actually the color of the powder of a mineral. It is called streak because the proper way to test for streak is to rub a mineral across a tile of white unglazed porcelain and to examine the color of the "streak" left behind.
Mineral Property #2: Luster
- The two major types of luster are metallic and nonmetallic.
- A mineral’s luster is the way in which light reflects from the surface.
Some other ways to describe luster are:
Dull - just a non-reflective surface of any kind
Earthy - the look of dirt or dried mud
Fibrous - the look of fibers
Greasy - the look of grease
Metallic - the look of metals
Pearly - the look of a pearl
Pitchy - the look of tar
Resinous - the look of resins such as dried glue or chewing gum

Silky - the look of silk, similar to fibrous but more compact
Submetallic - a poor metallic luster, opaque but reflecting little light
Vitreous - the most common luster, it simply means the look of glass
Waxy - the look of wax
What is the first thing someone notices about a mineral?



What do we call the color of the powdered mineral?



Which is more reliable: streak or color?

The first thing someone notices about a mineral is its color.
The color of the powdered mineral is called streak.
Streak is more reliable because color variances can occur within the same mineral.
Mineral Property #3: How It Breaks


-
Fracture
is the tendency of a mineral to break into irregular pieces.
- When a mineral breaks it does so either by
fracturing
or by
cleaving
.
-
Cleavage
is the tendency of a mineral to break along flat surfaces.
-
Crystal cleavage
is a smooth break producing what appears to be a flat crystal face.
Mineral Property # 4: Hardness
- A scale known as the Moh’s scale is often used:
- A mineral’s hardness is its resistance to being scratched.
Mineral Property #5: Density
- Density is the mass of a given space or in scientific terms the mass per unit of volume.
- Each mineral has a specific density.
For example, if you have two minerals of the same size one might be heavier than the other. The galena will be three times heavier than the same size of quartz.
First they use a balance to determine the mass of a sample.
Second, they place the mineral in water to see how much water it displaces.
* The volume of displace water = the volume of the sample

Third they use the following formula:
Density = Mass/Volume
Geologists measure density by the following:
If you break a mineral and it breaks into cubes, is it fracture or cleavage? Why?



If you break a mineral with a hammer and it falls apart into a million different pieces, is it fracture or cleavage? Why?




Name three things you can scratch talc with.




What is the formula for density?
If a mineral breaks into cubes it is cleavage because it broke along flat surfaces.
If a mineral break into a million different pieces it is fracture because the breaks are irregular.
Three things you can scratch talc with are fingernail, baby powder, and sandpaper, etc.
D = Mass/Volume
An acronym for remember the 5 mineral properties is:
S L C D F H
S
treak
Powdered Color
L
uster
How shiny
C
leavage
Breaks in sheets or blocks
D
ensity
How much mass in a given volume
F
racture
Just crumbles & breaks
H
ardness
Can be scratched by
ome
lamas
limb
own
unny
ills
COLLECTING INFORMATION:
COLLECTING INFORMATION:
COLLECTING INFORMATION:
COLLECTING INFORMATION:
COLLECTING INFORMATION:
COLLECTING INFORMATION:
COLLECTING INFORMATION:
COLLECTING INFORMATION:
COLLECTING INFORMATION:
FORMING A HYPOTHESIS:
Temperature, location, cooling time, position

will get smaller, larger
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