Unit 1 Lab Assignment (2)

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Chemistry

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Feb 20, 2024

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Unit 1 Lab Assignment Name Date 1/19/2024 Course ID ESC1000L 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: The image a shows a clean break, implying cleavage as the mineral breaks along the direction of the planes, creating a straight, geometric cut. B: Image b shows irregular breaks, which are why they are classified as fractures.

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: This shows that dolomite has a higher hardness than glass and glass. Glass has a hardness of 5.5 and glass has a hardness of 3 – 3.5 on the Mohs scale . Activity 1.2: Optical Properties of Minerals Question 3: Determine the streak of the samples below. Cinnabar:

To determine the streak of cinnabar, rub the mineral against an unglazed porcelain streak plate. Cinnabar is a red mercury sulfide mineral, and its streak is generally a distinctive scarlet to brownish-red color. Pyrite: the streak of pyrite is typically dark gray to black. Question 4: Calcite exhibits double refraction. Explain what that means. Response: When light passes through the calcite, it is split into two different rays of light and each follow a different path, This occur because the structure is no uniform in all directions(isotropic). 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:

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-Color: Sulfur is typically yellow, but it can also appear in various shades like pale yellow, lemon yellow - Odor: Sulfur has a distinctive smell, often described as a rotten egg odor - Flammability: Sulfur is combustible and can burn with a blue flame Magnetite: - Magnetism: Magnetite is strongly magnetic, and it can attract small pieces of iron. - Color: Magnetite is typically black or dark brown -Hardness: Magnetite is quite hard, with a hardness ranging from 5.5 to 6.5 on the Mohs scale.

Calcite: - Color: Calcite can be colorless, white, or various shades of pink, green, blue. - Hardness: Calcite has a relatively low hardness, around 3 on the Mohs scale. – Double Refraction: Calcite exhibits double refraction

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. Sampl e Hardnes s Streak Color Cleavage / Fracture Specifi c Gravity Luster Other Properties Name 1 3-5 White White To colorless Cleavage 2.7 Vitreou s Effervescenc e Calcite 2 6-9 Colorless Black- Brown Fracture 4-4.5 Dull strong birefringence Corundum 3 5.5-6.5 black Black and brown Fracture 5 pearly Magnetic Magnetite 4 2.5 white Green, black and white cleavage 2.8 vitreous translucent Biotite Mica 5 7 colorless colorless Fracture 2.6-3.5 Vitreou s can generate an electric charge Quartz 6 6-7 White yellow cleavage 3-3.5 pearly Gypsum is soluble in water Gypsum 7 1 white Grey and white cleavage 2.8 greasy softest mineral on the Mohs scale Talc 8 3-4 white Colorless , white, blue, green, yellow cleavage 4 vitreous fluorescence under ultraviolet light Fluorite 9 Lower than 2.5 white White Fracture 2.1-2.4 vitreous blocky cleavage Plagioclas e Feldspar 10 1.5 Black Grey- black cleavage 2.2 greasy High- Temperature Stability Graphite

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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

Hardness Streak Color Cleavage/ Fracture Specific Gravity Luster Name 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.)

Hardness Streak Color Cleavage/ Fracture Specific Gravity Luster Name 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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