Lab report of minerals PDF

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Manfang Wu Professor Ayers GEO 103 Feb 15th, 2021 Title: Minerals Introduction: In the most common minerals found in Earth's crust can be identified using basics physical properties like color, hardness, luster and streak. Some minerals which are found under same condition are likely to be found in same rocks and show similar properties by testing the physical properties of minerals. We can identify 90% of mineral types. So in this lab exercise, our purpose is to identify minerals an basic of their physical properties and classify them into these categories. Methods: Most minerals can be characterized and classified by their unique physical properties: hardness, luster, color, streak, specific gravity, cleavage, fracture, and tenacity. Hardness is a mineral's ability to resist being scratched. Minerals that are not easily scratched are hard. You test the hardness of a mineral by scratching its surface with a mineral of a known hardness. Luster describes the way light reflects off of the surface of the mineral. You might describe diamonds as sparkly or pyrite as shiny, but mineralogists have special terms to describe the luster of a mineral. They first divide minerals into metallic and non-metallic luster. Minerals like pyrite that are opaque and shiny have a metallic luster. Minerals with a non-metallic luster do not look like metals. One of the most obvious properties of a mineral is color. Color should be considered when identifying a mineral, but should never be used as the major identifying characteristic. Streak is the color of the powdered mineral, which is usually more useful for identification than the color of the whole mineral sample. Rubbing the mineral on a streak plate will produce a streak. A

streak plate can be made from the unglazed back side of a white porcelain bathroom or kitchen tile. Some minerals won't streak because they are harder than the streak plate. Specific gravity is the ratio between the mass (weight) of a mineral and the mass (weight) of an equal volume of water. A mineral's specific gravity (SG) can be determined by dividing its weight in air by the weight of an equal volume of water. For instance, quartz with a density of 2.65 is 2.65 times as heavy as the same volume of water. The way in which a mineral breaks along smooth flat planes is called cleavage. These breaks occur along planes of weakness in the mineral's structure. However, if a mineral breaks along an irregular surface, it does not have cleavage. When a mineral breaks irregularly, the breaks are called fractures. The breaks can be described as grainy, hackly (jagged), conchoidal (curved), or splintery. How well a mineral resists breakage is known as tenacity. Tenacity is described using these terms: ▪

Brittle - Mineral crushes to angular fragments (quartz).

▪

Malleable - Mineral can be modified in shape without breaking and can be flattened to a thin sheet (copper, gold).

▪

Sectile - Mineral can be cut with a knife into thin shavings (talc).

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Flexible - Mineral bends but doesn't regain its shape once released (selenite, gypsum).

▪

Elastic - Mineral bends and regains its original shape when released (muscovite and biotite mica).

Results:

Mineral Name

Possible Colors

Streak

Hardness

Cleavage (how many planes) or Fracture

HEFT Light, Medium, Heavy

Me

Fluorite

Green, yellow, purple

White

4

Cleaves

Medium

Vitr

Biotite

Brown

None

2.5-3

Cleaves 1 plane

Light

Vitr

Calcite

Clear to milky, orange, blue

White

3

Cleavage

Light

Gla

Feldspar

Gray, green orange

Colorless

6

Two planes of cleavage that meet at right angles

Light

Vitr

Graphite

Grey

Grey

1.2

Cleavage

Light

Alabaster Gypsum

Pinkish-white, white, grey, reddish-brown

White

1.5-2 scratches with fingernail

Cleaves

Light

Mineral Name

Possible Colors

Streak

Hardness

Cleavage (how many planes) or Fracture

HEFT Light, Medium, Heavy

M Pe

Me

Halite

Clear, white

None

2.5

Cleaves at right angles

Light

T

Hematite

Black, grey, reddish-brown

Reddish-brown

5.5-6.5

Fracture

Heavy

Me

Magnetite

Grey-black

Black

6

Non cleavage, but octahedral parting

Heavy

Muscovite

Clear, white, light brown

Colorless, light brown

2-2.5

Cleaves in 1 plane

Light

Gla

Pyrite

Golden-brassy, yellow

Greenish black

6-6.5

Fracture

Medium

Quartz

Clear, white, purple, rose, grey

None

7

No cleavage, but conchoidal fracture

Light

Satin Spar Gypsum

White, Grey

White

2

Fracture

Light

Selenite Gypsum

Colorless

White

2

Cleaves into 1 plane

Light

T

Talc

White, green

White

1

Cleaves

Light

Pe

Discussion: The importance of minerals in our everyday lives can be recognized all around us. From eating nutrient-rich foods to powering smartphones with copper, almost everything we use is a mineral resource. Here are a few common ways we use minerals today. Conclusion: In this lab, I used the Mineral Identification Table and the Mohs Hardness Scale to identify an assortment of minerals. Being able to identify minerals is important, because mineral identification is necessary to identify rocks and can be used to understand both the landscape and the geologic history of the area. For example identifying pyrite in a rock tells the geologist that volcanoes were once present and that conditions are favorable for finding silver and gold ores.

Vitr...