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Homework answers / question archive / Unit 1 Lab Assignment Activity 1
Unit 1 Lab Assignment
Activity 1.1: Mechanical Cohesion Properties of Minerals
Question 1:
Images (a) and (b) are two mineral samples, calcite and limonite respectively. Describe any cleavage or fracture exhibited in the samples and explain how you came to your conclusions regarding the samples.
Image a:
Image b:
Photos by L. Curtis – (a) Calcite (b) Limonite
A:
B:
Question 2:
Image (c) is a sample of dolomite. A student attempts to scratch the surface with his fingernail and is unable to do so. Then, he scratches the sample against a piece of glass, which remains unscratched. What assumptions can be made about the sample?
Image c:
Photo by L. Curtis – (c) Dolomite
C:
Activity 1.2: Optical Properties of Minerals
Question 3:
Determine the streak of the samples below.
Cinnabar:
Pyrite:
Question 4:
Calcite exhibits double refraction. Explain what that means.
Response:
Activity 1.3: Special Properties of Minerals
Question 5:
Below you will see images of Sulfur, Magnetite and Calcite. Using internet research, write an explanation for each sample about the special properties that could help a student to identify these minerals.
Sulfur:
Magnetite:
Calcite:
Activity 1.4: Identification of Minerals
Question 6:
Using the provided definitions and the identity tables below as a guide, identify the mineral samples given to you by your instructor in the Lab 1 Video.
Sample Hardness Streak Color Cleavage/ Fracture Specific Gravity Diaphaneity Other
Properties Name
1
2
3
4
5
6
7
8
9
10
Mineral Identification Tables
Metallic to Sub-Metallic Luster Minerals
Hardness Streak Color Cleavage/ Fracture Specific Gravity Other Properties Name
1 green to blue/gray gray Cleavage - 1 dir. 4.7 greasy feel Molybdenite
1 - 1.5 gray to black gray to black Cleavage - 1 dir. 2.25 greasy feel Graphite
1.5 - 2 gray to black indigo blue Cleavage – 1 dir. 4.68 iridescent yellow and red Covellite
2.5 Gray gray Cleavage – 3- dir. 7.5 Galena
2.5 - 3 black to lead gray black to lead gray Fracture 6.46 brittle Chalcocite
3 gray-black bronze, iridescence that is red-purple Fracture 5.0 Bornite
3.5 – 4 green-black brassy yellow, often tarnished Fracture 4.2 most common copper mineral Chalcopyrite
4 – 5.5 yellow-brown to red yellow-brown, orange-brown, dark brown Fracture 2.7-4.3 Limonite (Goethite)
4.5 - 5 reddish-brown steel-gray to red-brown Fracture 4.5 most common iron mineral Hematite
5.5 – 6.5 Black black Fracture 5.0 strongly magnetic Magnetite
6 – 6.5 green to brownish black gold to pale brassy yellow Fracture 5.0 Pyrite
Non-Metallic Luster Minerals
Hardness Streak Color Cleavage/ Fracture Specific Gravity Luster Name
1 White white Cleavage – 1 dir. 2.8 pearly or greasy / dull Talc
1 – 2.5 Yellow yellow Fracture pearly Sulfur
2 White colorless, white, gray, yellow Fracture 2.1 – 2.4 vitreous Gypsum
2.5 White colorless, blue, yellow-blue Cleavage – 3 dir. 2.2 – 2.4 vitreous Halite
2.7 – 3.1 gray to white black, dark green or brown Cleavage – 1 dir. 2.8 vitreous or pearly Biotite Mica
2.7 - 3 White gray, green or colorless Cleavage – 1 dir. 3.0 vitreous Muscovite Mica
3 White colorless or white Cleavage – 3 dir. 2.7 vitreous Calcite
3 – 3.5 White colorless or white Cleavage – 2 dir. 4.5 vitreous Barite
3 – 3.5 White white, gray, brown, pink Cleavage – rhombic vitreous or pearly Dolomite
3.5 - 4 Green Green Fracture 4.0 silky to dull Malachite
3.5 – 4 light yellow to brown dark brown, black or yellow Cleavage – 6 dir. 4.0 resinous to sub-metallic
adamantine Sphalerite
4 White colorless, white, yellow, purple, blue, green Cleavage – 4 dir. 3.0 vitreous Fluorite
5 White yellow, green, blue, brown Fracture vitreous Apatite
6 Gray dark green to black Cleavage – 2 dir. vitreous Augite (Pyroxene)
6 gray-white dark green, black, or brown Cleavage – 2 dir. 3.0 vitreous Hornblende (Amphibole)
6 white or gray olive green to brown Fracture vitreous to adamantine Olivine
6 colorless to white white to dark gray Cleavage – 2 dir. 3.0 vitreous Plagioclase Feldspar (Albite, Labradorite, etc.)
6 colorless to white white, tan, red, orange, green, colorless Cleavage – 2 dir. 2.5 vitreous or pearly Potassium Feldspar (Orthoclase, Microcline)
7 colorless colorless, white, gray, purple, pink, black, yellow, green Fracture 2.6 – 3.5 vitreous Quartz
9 colorless gray, brown, blue, red, colorless Fracture 4.0 – 4.5 dull to vitreous, adamantine Corundum
8 colorless to white clear, brown, black, tan Cleavage - Orthorhombic 3.5 vitreous Topaz
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