Minerals Properties Lab for journal

Luster

Mineral name	Chemical formula	Sample
pyrite	FeS2
chalcedony	SiO2
limonite	Fe2O3 · H2O

1. Describe the luster of each sample.
2. Which two of these have a nonmetallic luster?

Color

Mineral name	Chemical formula	Sample
azurite	Cu2(CO3)2(OH)2
fluorite	CaF2
amphibole	CaNaMg4Fe3Si6O22(OH)2

1. Describe the color of each sample.
2. Looking at these samples, make a prediction about the color of minerals containing copper.
3. Why isn't color a reliable identifier of minerals?

Streak

Mineral name	Chemical formula	Sample
pyrite	FeS2
specular hematite	Fe2O3

1. Describe the streak color of each sample.
2. What is surprising about the color of one of these streaks?

Cleavage / Fracture

Mineral name	Chemical formula	Sample
muscovite	KAl3Si3O10(OH)2
quartz	SiO2
calcite	CaCO3

Do not break these minerals - look at evidence of how they have broken in the past.

1. Does the sample mineral exhibit cleavage or fracture?
2. Does table salt exhibit cleavage or fracture?

Heft

Mineral name	Chemical formula	Heavier or lighter?
halite	NaCl
galena	PbS

Rather than measure the actual specific gravity of the mineral samples, we will gauge the 'heft' or the relative weight of the samples.

1. Which sample is heavier?
2. How would looking at the chemical formula help you answer heavier or lighter?
3. Does halite exhibit cleavage or fracture?

Crystal Form

Mineral name	Chemical formula	Sample
goethite	HFeO2
malachite	Cu2CO3(OH)2

1. Does the sample mineral exhibit a regular (repeating pattern) or irregular crystalline shape?
2. Does halite have a regular or irregular crystalline form?

Hardness

Mineral name	Chemical formula	Sample
mineral a	Al2O3
mineral b	Mg3Si4O10(OH)2
mineral c	CaF2

Procedure:

1. With only these three tools to use you will only be able to give a range of Mohs hardness. i.e " mineral A is between 2.5 and 3.5
2. See if the mineral first scratches your fingernail. If it doesn't it must be softer than....
3. If it scratches the penny then it must be harder than...
4. If it scratches glass then it must be harder than...
5. Describe the range of Mohs Hardness numbers of each sample.

Wow:   Mineral 'a' is used to make sandpaper and in a pure form is also called a ruby!

Special Properties

Mineral name	Chemical formula	Sample
magnetite	FexOy
sulfur	S

1. Describe a special property of each sample.
2. Why are there variables (x and y) in the chemical formula for magnetite?
3. What other minerals in this lab might have the same special property as magnetite?
4. Why do you think this?