The Study of Minerals - Lab 1

Name the physical property described by each of the following statements.

Breaks along smooth planes: Cleavage Scratches glass: Hardness Shines like a metal: Luster Scratching produces a red powder: Streak Looks like broken glass: Fracture

Which, if any, of the minerals you identified are both rock forming and economic?

Calcite and Quartz

How many directions of cleavage are present on the specimen?

Cleavage in three directions

The five samples are specimens of the mineral fluorite. Is color a diagnostic or ambiguous property of fluorite?

Color is an ambiguous property of fluorite because it is a different specimens (color) of the same mineral (fluorite).

Based on the samples of quartz, explain why color is not a diagnostic property of this mineral.

Color is not a diagnostic property of quartz because the color varies. Quartz can have the same color as other minerals making it a not so good diagnostic character.

What physical feature most distinguishes biotite mica from muscovite mica?

Color. Biotite is black and Muscovite is light colored.

Which if the crystals (A, B, C, or D) in the igneous rocks shown are feldspar crystals, and which are quartz?

Feldspar: B (C, D) Quartz: A (A,B)

Provide an economic use for each mineral listed:

Galena: Ore of Lead Hematite: Ore of Iron Graphite: Dry Lubricant Sphalerite: Ore of Zinc Gypsum: Dry Wall Calcite: Marble, cement.

For each mineral listed below, list at least one diagnostic property that could be used to help distinguish this mineral from others.

Halite: Salty taste Galena: Cubic shape crystal Magnetite: Magnetic Muscovite: Thin and flexible Hematite: Red lines Fluorite: Fluorescent color Talc: Smooth and pearly like Graphite: Feels Slippery Calcite: Reacts to hydrochloric

Write a generalization that describes how the angle between crystal faces relates to the size and/or shape of the sample.

It seems that the angles between the crystal faces d not change.

I a mineral can be scratched by a penny but not by a human fingernail, what is its hardness on the Ohs scale?

2.5 - 3.5

Select three mineral specimens from the set provided by your instructor. Determine the hardness of each mineral.

> 6.5 Quartz <2.5 Talc >6.5 Corundum

What do we mean when we refer to a mineral's tenacity?List three terms that describe tenacity.

A mineral's tenacity is a mineral's resistance to breaking or falling apart. Three terms are: Brittle, sextile and elastic

Describe the simple chemical test that is useful in the identification of the mineral calcite.

A small drop of dilute hydrochloric acid is dropped on the Calcite to verify if it reacts in a "fizz", known as the acid test.

Identify each specimen (A or B) next to its appropriate description below.

Crystal form of fluorite: A Cleavage specimen of fluorite: B

Describe the crystal form (habit) of this specimen.

Cubic

What term is used to describe the shape of a mineral that has three directions of cleavage that intersect at 90-degree angles?

Cubic

What terms used to describe the tenacity of muscovite?

Elastic

Describe the cleavage of the minerals listed below. Include the number of directions and degrees of cleavage angles.

Muscovite: Perfect, 1 plain, no angle Calcite: 3 plains, less 90 degrees Halite: 3 directions, 90 degree angle Feldspar: 2 directions, 90 degree angle

Based on the streak of this sample, how would you describe its luster?

Non-Metallic

Use the mineral identification key to identify a mineral that is non metallic, dark colored, harder than glass, lacking cleavage, and green in color.

Olivine

Name a mineral that exhibits the physical properties listed.

One direction of cleavage: Gypsum Striations: Plagioclase Feldspar Multiple Colors: Calcite Cubic Cleavage: Galena Nonmetallic, vitreous luster: Quartz Fracture: Quartz Metallic Luster: Galena

Describe the cleavage of the mineral shown.

One plain, thin transparent layers and no angles.

Compare and contrast the terms Opaque, Translucent, and Transparent.

Opaque, like hornblende, is when no light is transmitted. Translucent, like Biotite Mica, is when light, but not an image is transmitted. Transparent, like Calcite, does both light and image visibility.

Based in what you can determine from this photo. Identify this mineral:

Pyrite

List the two most common rock-forming mineral groups:

Quartz and Feldspar

Which of these appear to be rocks, and which are most likely minerals?

ROCKS: B MINERALS: A, D, C

Use the geologic definition of a mineral to determine which of the items listed are minerals and which are not.

Rain Water - No - Rain water is not a solid substance, it's a liquid. Quartz - Yes - It is naturally occurring & has crystalline shape. Coal - No - Coal is organic made from decomposed plants. Silver - Yes - Silver is solid, occurs naturally and is inorganic. Wood - No - Wood is an organic material and is not crystalline in structure. Synthetic diamonds - No - It is not naturally occurring. Halite - Yes - It is naturally occurring from NaCl.

For both samples, describe the color of the specimen and the streak.

Specimen A: Brown Color, Leaves Brown Mark Specimen B: Black Color, Leaves Brown Mark

Select one of the following terms to describe the crystal shape, or habit, of each specimen shown.

Specimen A: Fibrous Habit Specimen B: Habit Bladed Specimen C: Banded Habit Specimen D: Cubic Crystals

Use the Ohs scale to identify which is fluorite and which is topaz.

Specimen A: Fluorite Specimen B: Topaz

Do they exhibit a streak? If so, is the streak the same color as the mineral specimen?

Specimen A: Gray, Stay Marks (Smoky Quartz) Specimen B: Brown, No Marks (Corundum) Specimen C: Gold, Gold Marks (Chalcopyrite)

What term is applied to the lines on this sample?

Striations

Are the angles about the same for each quartz specimen, or do they vary from one sample to another?

The angles vary from one sample to another.

Do the cleavage directions meet at 90-degree angles other than 90 degrees?

The cleavage directions meet at angles other than 90 degrees

A photo of Agate, a variety of quartz composed of microscopically small crystals, is provided. Based on this image, describe the habit of this sample.

This sample has no cleavage and no angles. It is banded.

How many cleavage surfaces are present on the specimen?

Three

List the five characteristics an Earth material must have in order to be considered a mineral.

a. Naturally Occurring b. Generally Inorganic c. Solid Substance d. Orderly Crystalline Structure e. Definite chemical composition that allows for some variation